Rainwater Butts vs Underground Tanks and Which System Suits Your Property

Another dry weekend in the garden, sprinkler droning away to keep your lawn alive, with half your brain wondering if that really is necessary and the other half calculating how many pounds that’s adding to the water bill. Isn’t there a better way to do things?

Rainwater harvesting isn’t a new idea, but these days it’s grown far beyond the standard plastic water butt lurking behind the shed. You can get small standalone tanks for rainwater capture but the biggest decision you face is whether you’re happy with something simple that just fills up with a bit of rain for your roses, or if you’d rather invest in a proper system that could significantly cut your mains water usage.

It’s more complicated than choosing between water butts and underground tanks, but also hugely dependent on budget. How much water do you actually want to save? How much space do you have? Are you planning on living in this house long enough to justify a bigger installation? Here’s how to figure out if you need a water butt or an underground rainwater harvesting system.

## Water Butt or Underground Tanks? How They Work

These systems fall into two categories – surface water collection and storage, and underground storage systems.

**Water Butt Systems**: Water butts are the simplest form of rainwater harvesting system. They collect run off from your roof via your guttering, normally with a diverter fitting that sends most of the water into your butt with overflow going down the downpipe as normal. You can get most water butts in 100 litre and 250 litre sizes (Which) which doesn’t sound like much until you realise that watering the average UK garden uses between 300 and 1000 litres per hour using a hosepipe (Thames Water). Your average water butt will give you around 15 minutes of “normal” hosepipe gardening use before it runs out.

**Underground Systems**: Underground rainwater harvesting tanks work on the same principle but with enough storage space to make a real difference. These tanks can range from 1000 litres all the way up to 10000 litres(Direct Water Tanks) which for comparison is about the size of your average heated petrol car. Just like water butt systems, the water is collected from your roof via gutters. It may pass through additional filters to remove leaves and other debris before it enters your underground storage tanks.

The main difference here is that underground tanks don’t freeze in winter and they don’t take up any valuable space in your garden.

**Supply and Usage**: Water butt systems normally rely on gravity feed via a tap at the bottom of the tank. Unless you want to lug around watering cans all the time your water butt needs to be positioned above where you actually want to use the water. Underground tanks can use pumps to provide mains pressure water that can supply your toilets, washing machines and outside taps.

## Which rainwater harvesting system is best for you?

Item	Benefits	Typical Usage	Installation Cost	Property Type
Water Butt System	Save on Outdoor Water Use. Garden Resilience During Drought Restrictions. Reduced Visual Pollution	Container plants and water conserving gardens	£50-150	Most property types
Large Capacity Underground Tank	Save on Overall Water Bill. Future Proof Your Home Against Water Restrictions. Increase Home Value	Toilet Flushing. Laundry and Washing Machines. Outside Use (taps and garden)	£2000-6000	Detached or Large Gardens

The latter systems can provide up to 50 percent of a homes non drinking water requirements (Waterwise) which covers toilet flushing, laundry, washing cars and gardening.

Water butt systems are just garden irrigation systems that happen to save you a few quid on the bill. Underground rainwater tanks are your alternative household water supply that just so happen to include watering the garden.

Obviously one is a lot more complex, costly and involved than the other.

### What Can You Actually Do with a Water Butt?

You can save some money on outdoor water use. Unless you have a football pitch for a garden a water butt is not going to completely take over your household water requirements.

Water Butt vs Underground Rainwater Tank

#### Basic Water Butt System

Lets start with a basic system. A standard 200 litre water butt will set you back £40-80, and you’ll need another £15-25 for a diverter kit to connect to your downpipe. Installation is literally a job you can do yourself over a weekend. You’ll need to position your water butt on something that keeps it upright. A concrete slab will do, or you can simply surround the butt with hardcore gravel. If possible position it up off the ground to give you more pressure from the tap at the bottom. Connect the diverter to your downpipe and then connect the butt to the diverter kit. The diverter diverts away the first bit of water that comes through when it rains. This first flush helps clear debris off your roof that might otherwise end up in your water butt. Once you’ve filled the butt with rainwater it diverts future rainfall back into your standard drainage system.

Thats it. Install fill with rain, then use that water for washing the car and watering anything that doesn’t need watering every day. Summer usually isn’t that long so your butt should refill several times over the course of the year.

You can link multiple water butts together to increase storage. Three 200 litre butts chained will give you 600 litres of storage, but they will also take up quite a lot of room and become a pain to fit. You’re now looking at £150-£250 for butts and connectors but you’re still well under a £300 all in cost.

##### Water butt performance

The largest UK rainfall for a month is around 200mm. A typical house has 40 square metres of roof. Multiply that together and you get 8000 litres of rain that could be collected in a single month. A typical 200 litre butt will collect 600 litres from that roof area. That means you can expect to refill an average sized water butt about once per month during wetter months in the UK.

Once again thats only if your butt is positioned perfectly and you have regular rainfall. Summer isn’t that long so you should get at least 2 full water butt supplies per year. That’s enough water to easily look after potted plants and wash the car once in a while. It probably won’t cut your overall bill by much.

If you’re serious about water butts you’ll want to look at large water butt options (8000 Litre Butts). These aren’t cheap but they do offer around 50% more storage than most people realise they need. Anything over 200 litres and you’ll definitely want a watering can.

##### Cost and Maintenance

Your water butt will probably last 25+ years before problems start (Manufacturers Data). If you maintain your butt properly you shouldn’t have any issues. Just make sure you clean your butt out every couple of years. You should also periodically check and maintain the tap mechanism to prevent it sticking. Finally, keep leaves out of the water butt by ensuring the diverter is maintained and working correctly. Leaves are the biggest problem with water butt ownership.

Water butt systems are popular for a reason. Over 3 million have been distributed to householders by UK water companies (Water UK). That’s because they’re cheap and effective entry level solutions for rainwater harvesting.

They won’t completely eliminate your water bill, but you can save money instantly by switching to rainwater for your outdoor use. As well as giving you better control over your garden during hosepipe bans and drought restrictions, a water butt is a great first step towards cutting down on your water use.

If you really have your heart set on completely replacing your mains water you’ll need to start thinking underground (below).

### Large Budget: Underground Rainwater Tank Systems

Underground systems quickly start to turn your rainwater harvesting plans into a proper alternative water supply. These tanks can really start to make a difference to your overall water bill, especially if you use them to supply your toilet and laundry.

Here’s how.

As with water butt systems these setups start with your roof guttering. Instead of diverting water into a tank on your property you’ll divert it to an underground storage tank. First flush diverter systems are recommended to keep leaves and debris out of your tank. As you’ve guessed by now these tanks sit underground so you don’t have to worry about them freezing or taking up space in your yard.

Whilst above ground tanks rely on gravity feed, underground tanks require pumps to deliver the water to where you need it. These pumps push water around your house at mains pressure so you can just attach toilet supply hoses and even laundry connections. Finally some systems include a standard connection to your mains water supply that automatically kicks in once your tank runs empty. These setups are more complex but can provide a completely seamless supply that drastically cuts your water bill.

#### Underground Tank Installation Costs

So how much does one of these setups cost? Well as you’ve probably realised by now, underground tanks start at around £2500 or more (Checkatrade). They’re expensive for a few reasons. Most obviously they require excavation and tank bedding. You’ll also need pumps, controls and additional plumbing to connect your tank into your homes plumbing system.

Don’t forget, anything that connects to your internal household plumbing also needs Building Regulations approval. This installation isn’t something you can do yourself. You’ll need groundwork contractors to dig the hole and properly install your tank, as well as qualified plumbers to connect it all up. Expect some disruption to your garden whilst its installed, although most installers will have your entire system fitted in less than 1 week.

#### Water Quality and Supply

Obviously rainwater wont magically become mains quality when you store it underground. These tanks do include better filters to help with debris and the water wont contain fluoride or other added substances. The water quality will be good enough for toilet and laundry use, but not for drinking straight from the tap.

With the right pumps you can use this water supply to pretty much any outdoor tap you have though. These systems might also include UV Sterilisation or other water treatment options if you want better water quality. This obviously costs more but its an option.

Really sophisticated systems can hook directly into your plumbing to supply toilets and laundry automatically. Think of it like your internal plumbing having two water supplies. They even have clever overfills so when your underground tank runs empty your regular water supply automatically kicks back in.

If you’re worried about your water quality during long dry spells you can connect your rainwater tank straight to the mains water supply. Then when rain is scarce you still have backup supply.

There are pros and cons to both approaches. More complex systems reduce installation size and labour costs, but hooking your tank supply into household plumbing adds significant complexity and cost.

### Installation Mistakes to Avoid

1. Assuming one water butt is enough. We see this a lot. People buy the smallest water butt available and expect it to cover all their water needs. It won’t. Remember that average garden watering uses around 1000 litres per hour. A single water butt might save you some money on outdoor water use but it won’t support a lot of garden watering.

2. Positioning your water butt awkwardly. If your water butt isn’t well positioned you’ll spend your weekends wrestling with watering cans. You need to think about gravity when you position your butt. Just because your downpipe is in the corner of your garden doesn’t mean you should put your butt there. Water butts work best when they’re as high up as possible. Position them where you can use the water easily too.

3. Forgetting overflow arrangements. You need to plan for overflow. Every system will have some sort of overflow pipe that diverts away excess rainwater once your tank is full. Make sure this doesn’t drain towards your house. Rainwater harvesting systems for underground tanks are more likely to suffer from this mistake. You don’t want excess water pooling under your tank and softening the ground it sits in.

4. Pumping up basic butt systems. Add a few pumps, filters and automatic controls to your basic water butt and watch your reliability issues start. Just because you CAN make your water butt automated doesn’t mean you SHOULD. Additional complexity costs more money, takes up more room and is prone to breaking down. Only add pumps and automatic controls if you need mains water pressure for your intended use.

5. Going underground without planning for dry spells. You can spend thousands on an underground system that sits empty all summer because you don’t live in a rainy climate. Connect your tank to your main water supply. Either install automatic systems that switch over for you or have an external tap you can switch back and forth.

### Research Backing this Guide

CIRIA research showed that water harvesting systems reduced stormwater runoff by up to 60% (CIRIA). Preventing stormwater runoff helps with local flood prevention as well as providing water harvesting benefits.
The water industry reported that over 3 million water butts have been distributed through various schemes (Water UK). Schemes that are run by water companies and offer water butts for free or heavily subsidised prices.
Peter Simpson compared water butt vs underground system installation costs (Homebuilding and Renovating). Above ground rainwater harvesting systems remain significantly cheaper than their underground counterparts.
The average water butt will supply garden watering needs for pots and potted plants (Uni of Cardiff). Larger gardens will require additional storage.
A rainwater harvesting report from waterwise.org.uk confirmed systems can provide up to 50 percent of non drinking water (Waterwise). That covers toilets, laundry and outdoor use.
The same report shows outdoor irrigation makes up 10 percent of average homes water usage. That means rainwater can cover all of your non drinking water use.
The official body for qualified plumbers UK trades.org.uk explained why you must inform your installer of any soakaway systems (UK Trades). Rainwater harvesting systems for underground tanks will need to know where your soakaways are located.
The leading trade accreditation site in the UK Checkatrade provided rainwater harvesting system costs (Checkatrade). As you can see above ground tanks are significantly cheaper.
Instant Gardener posted before and after photos of above ground tanks (Instant Gardener). A nice visual reference for why you may prefer underground tanks.
DWC praised the longevity of properly installed rainwater tanks (DWC). Tanks normally last 25+ years with very little maintenance.
RICS explained how underground tanks help maintain property values (RICS). Mental health is boosted by being outside and rainwater tanks aren’t visible in most gardens.

Installing rainwater harvesting doesn’t need to cost the earth. You can spend less than £100 on a solution that starts saving you money instantly, or you can convert your home to completely free yourself from the water bill. Whilst the former is much easier and cheaper the latter is never more than 5 years away.

House Style	Best Solution
Terraced house with small garden	Single or multiple water butts. Limited space here so water butts are often the only option.
Semi-detached with medium garden	Water butt or underground system. Both can work well here depending on your budget and watering needs.
Detached house with large garden	Large garden = underground tank Probably the best option. You likely have the space and the water usage to justify installation.
New Build Property	Build it in! Have you considered rainwater tanks when designing your extension? Contact your builder.
Rentals	You may not even be allowed to modify the plumbing in your rental property. Water butts aren’t much use unless you can position them where you need water.

Which rainwater harvesting system is right for your home?

**Water Butt High Level Summary**

* Immediate Water Bill Savings: Even basic water butt systems can instantly reduce your water bill by switching outdoor water use to rainwater. Outdoor watering costs £300 per year or more for most households so you’ll save £30-60/year on water bills. That pays for the water butt itself in 2-3 years. Underground systems saving 50% of non drinking water can save you up to £400/year.
* Garden Resilience During Water Restrictions: Water butt systems keep your garden irrigated during hosepipe bans and drought restrictions. When your water supply is cut you still have access to rainwater stored from previous weeks and months.
* Less visual pollution: Underground tanks won’t spoil your garden design like a row of water butts.

Best Suited Properties

Water butts are suitable for any property with downpipe access. Seriously, any house will benefit from at least one water butt. Consider starting with a single butt then increasing your rainwater storage capacity over time.<|repo_name|>CharlesHall89/digitalocean-blog<|file_sep|>/rainwaterharvesting-system/content/avoid-these-common-costly-installation-mistakes.md
—
title: Avoid these common (and costly) installation mistakes
date: 2019-02-08T17:39:13.000Z
permalink: “/avoid-these-common-costly-installation-mistakes/”
description: These mistakes cost people thousands of pounds every year
lead: These mistakes cost people thousands of pounds every year by invalidating warranties, reducing longevity and flooding their gardens.
author: Leon Mann
image: https://uploads-ssl.webflow.com/5dcfe315c56fb0095eaa2888/5dcfe315c56fb0095eaa38d6_1583184732190-imageedit_11_2081276907.jpg
—

Installing a rainwater harvesting system can reduce your water bills and it’s actually pretty simple once you know how. However there are a few things people tend to do wrong that can end up costing them hundreds, if not thousands of pounds. From bad performance to completely invalidating your product warranty these installation mistakes are easy to avoid.

1. Assuming one water butt is enough

We see this a lot. People buy the smallest water butt available and expect it to cover all their water needs. It won’t. Remember that average garden watering uses around 1000 litres per hour. A single water butt might save you some money on outdoor water use but it won’t support alot of garden watering.

2. Positioning your water butt awkwardly

If your water butt isn’t well positioned you’ll spend your weekends wrestling with watering cans. You need to think about gravity when you position your butt. Just because your downpipe is in the corner of your garden doesn’t mean you should put your butt there. Water butts work best when they’re as high up as possible.

Position them where you can use the water easily too.

3. Forgetting overflow arrangements

You need to plan for overflow. Every system will have some sort of overflow pipe that diverts away excess rainwater once your tank is full. Make sure this doesn’t drain towards your house.

Underground rainwater harvesting systems are more likely to suffer from this mistake. You don’t want excess water pooling under your tank and softening the ground it sits in.

4. Pumping up basic butt systems

Add a few pumps, filters and automatic controls to your basic water butt and watch your reliability issues start. Just because you CAN make your water butt automated doesn’t mean you SHOULD.

Additional complexity costs more money, takes up more room and is prone to breaking down. Only add pumps and automatic controls if you need mains water pressure for your intended use.

5. Going underground without planning for dry spells

You can spend thousands on an underground system that sits empty all summer because you don’t live in a rainy climate. Connect your tank to your main water supply. Either install automatic systems that switch over for you or have an external tap you can switch back and forth.

If you’ve got any questions about rainwater harvesting or setting up your own system let us know @expertconsultancy on twitter.<|repo_name|>CharlesHall89/digitalocean-blog<|file_sep|>/rainwaterharvesting-system/content/how-to-set-up-your-own-rainwater-harvesting-system.md
—
title: ‘How To Set Up Your Own Rainwater Harvesting System’
date: 2019-01-30T19:31:04.000Z
permalink: “/how-to-set-up-your-own-rainwater-harvesting-system/”
description: Learn how to set up a rainwater harvesting system to save money on
your water bill.
lead: Interested in saving money on your water bill but don’t know where to start?
Rainwater harvesting might be the solution you’re looking for. Read our full guide.
author: Leon Mann
image: https://uploads-ssl.webflow.com/5dcfe315c56fb0095eaa2888/5dcfeb10c56fb01506aa2900_1581409279766-rainfall-chart.jpg
—

Standing in the garden during another dry weekend, watching the sprinkler desperately trying to keep your lawn alive. You start to wonder if it’s really necessary. Half your brain asks that question while the other half calculates how many pounds that’s adding to the water bill.

Isn’t there a better way to do things?

Rainwater harvesting isn’t a new idea, but these days its gone far beyond the standard plastic water butt lurking behind the shed. You can get small standalone tanks for rainwater capture but the biggest decision you face is whether you’re happy with something simple. Just enough rainwater to fill up your watering cans or would you rather invest in a proper system that could significantly cut your mains water usage.

This decision can cause problems for people. It’s more complicated than choosing between water butts and underground tanks, but also hugely dependent on budget. How much water do you actually want to save? How much space do you have? Are you planning on living in this house long enough to justify bigger installation costs?

Here’s a simple guide to help you figure out if you need a water butt or an underground rainwater harvesting system.

Water Butt or Underground Tanks? How They Work

These systems fall into two categories.

Surface water collection and storage.
Underground storage systems.

Water Butt Systems: Water butts are the simplest form of rainwater harvesting system. They collect run off from your roof via your guttering, normally with a diverter fitting thats sends most of the water into your butt. Overflow goes down the downpipe as normal.

You can get most water butts in 100 litre and 250 litre sizes (Which) which doesn’t sound like much until you realise that watering the average UK garden uses between 300 and 1000 litres per hour (Thames Water) using a hosepipe. Your average water butt will give you around 15 minutes of “normal” hosepipe gardening use before it runs out.

Underground Systems: Underground rainwater harvesting tanks work on the same principle but with enough storage space to make a real difference. These tanks can range from 1000 litres all the way up to 10000 litres(Direct Water Tanks) which for comparison is about the size of your average heated petrol car.

Just like water butt systems, the water is collected from your roof via gutters. It may pass through additional filters to remove leaves and other debris before it enters your underground storage tanks.

The main difference here is that underground tanks don’t freeze in winter and they don’t take up any valuable space in your garden.

Supply and Usage: Water butt systems normally rely on gravity feed via a tap at the bottom of the tank. Unless you want to lug around watering cans all the time your water butt needs to be positioned above where you actually want to use the water.

Underground tanks can use pumps to provide mains pressure water that can supply your toilets, washing machines and outside taps.

The latter systems can provide up to 50 percent of a homes non drinking water requirements (Waterwise) which covers toilet flushing, laundry, washing cars and gardening.

If your just watering the garden water butt systems are just garden irrigation systems that happen to save you a few quid on the bill. Underground rainwater tanks are your alternative household water supply that just so happen to include watering the garden.

Naturally one is a lot more complex, costly and involved than the other.

What Can You Actually Do with a Water Butt?

You can save some money on outdoor water use. Unless you have a football pitch for a garden a water butt isnt going to completely take over your household water requirements.

Basic Water Butt System

If possible position it up off the ground to give you more pressure from the tap at the bottom. Connect the diverter to your downpipe and then connect the butt to the diverter kit.

The diverter diverts away the first bit of water that comes through when it rains. This first flush helps clear debris off your roof that might otherwise end up in your water butt. Once you’ve filled the butt with rainwater it diverts future rainfall back into your standard drainage system.

Thats it. Install, fill with rain, then use that water for washing the car and watering anything that doesn’t need watering every day. Summer usually isn’t that long so your butt should refill several times over the course of the year.

You can link multiple water butts together to increase storage. Three 200 litre butts chained will give you 600 litres of storage, but they will also take up quite a lot of room and become a pain to fit together. You’re now looking at £150-£250 for butts and connectors but you’re still well under a £300 all in cost.

Water butt performance

That means you can expect to refill an average sized water butt about once per month during wetter months in the UK.

Once again thats only if your butt is positioned perfectly and you have regular rainfall. Summer isn’t that long so you should get at least 2 full water butt supplies per year. Thats enough water to easily look after potted plants and wash the car once in a while. Its probably still not going to cut your overall bill by much.

Cost and Maintenance

Your water butt will probably last 25+ years before you start to have any problems (Manufacturers Data). If you maintain your butt properly you shouldn’t have any issues. Just make sure you clean your butt out every couple of years. You should also periodically check and maintain the tap mechanism to prevent it sticking.

Finally keep leaves out of the water butt. Leaves are the biggest problem with water butt ownership. Ensure the diverter is maintained and working correctly.

They won’t completely eliminate your water bill but you can save money instantly by switching to rainwater for your outdoor use. As well as giving you better control over your garden during hosepipe bans and drought restrictions. A water butt is a great first step towards cutting down on your water use.

If you really have your heart set on completely replacing your mains water you’ll need to start thinking underground.

Large Budget: Underground Rainwater Tank Systems

Underground systems quickly start to turn your rainwater harvesting plans into a proper alternative water supply. These tanks can really start to make a difference to your overall water bill. Especially if you use them to supply your toilet and laundry.

Here’s how.

As you’ve guessed by now these tanks sit underground so you don’t have to worry about them freezing or taking up space in your yard.

Finally some systems include a standard connection to your mains water supply that automatically kicks in once your tank runs empty. These setups are more complex but can provide a completely seamless supply thats going to drastically cut your water bill.

Underground Tank Installation Costs

So how much does one of these setups cost? Well as you’ve probably realised by now, underground tanks start at around £2500 or more (Checkatrade). They’re expensive for a few reasons.

Most obviously they require excavation and tank bedding. You’ll also need pumps, controls and additional plumbing to connect your tank into your homes plumbing system.

Dont forget, anything that connects to your internal household plumbing also needs Building Regulations approval. This installation isn’t something you can do yourself. You’ll need groundwork contractors to dig the hole and properly install your tank as well as qualified plumbers to connect it all up.

Expect some disruption to your garden whilst its installed although most installers will have your entire system fitted in less than 1 week.

Water Quality and Supply

Obviously rainwater isn’t going to magically become mains quality when you store it underground. These tanks do include better filters to help with debris and the water wont contain fluoride or other added substances.

The water quality will be good enough for toilet and laundry use but not for drinking straight from the tap.

Really sophisticated systems can hook directly into your plumbing to supply toilets and laundry automatically. Think of it like your internal plumbing having two water supplies.

They even have clever overfills so when your underground tank runs empty your regular water supply automatically kicks back in.

If you’re worried about your water quality during long dry spells you can connect your rainwater tank straight to the mains water supply. Then when rain is scarce you still have backup supply.

Theres pros and cons to both approaches. More complex systems reduce installation size and labour costs. but hooking your tank supply into household plumbing adds significant complexity and cost.