It feels like once you’ve paid for your rainwater harvesting system and connected the pipes that the hard work is over. Switch it on and suddenly you’re harvesting hundreds of litres of water each month that would otherwise cost you a fortune.
Here’s the thing though, nobody tells you this when you first install your system. The difference between a system that saves you money for two decades and a money pit that loses you hundreds of pounds each year comes down to maintenance.
I maintain two rainwater systems; the one on my Victorian terrace house and a smaller system on my parents’ bungalow that I helped install. Between the two systems I made pretty much every mistake in the book and suffered some pretty costly setbacks because of it. So read on to avoid making the same mistakes I did…
You’ve got algae blooms that turned your 5000 litre storage tank into pond water.
You forget to run your pumps for months and they fail you when you get the wettest week of the year.
You clear blockages from first flush diverters that have become mini ecosystems.
Rainwater harvesting maintenance isn’t hard. In fact each task only takes minutes to do. But timing is everything. Get the timing wrong and your maintenance will not only take up more of your time than you save with rainwater; it could even begin to cost you money. Get it right and your rainwater harvesting system pretty much maintains itself with just an hour or so of work spread throughout the year.
Looking after every last drop of household water? Then don’t forget to read [our comprehensive guide to conserving water around the home](/).
## Rainwater Harvesting Maintenance Explained
Rainwater harvesting maintenance is easy when you know how things go wrong if you let them. Firstly, it’s not about being obsessive neat freak. If you keep on top of this list of tasks your rainwater harvesting system will be fine.
Prevent algae growth by keeping tank covers sealed and clear. Algae needs sunlight to grow, so any light creeping into your tank indicates a hole somewhere. Look out for cracks or gaps around tank lids and UV lamp fittings. Gaps as small as 5mm are enough for light to penetrate. Replace tanks with lots of small cracks or lids that don’t seal properly.
Deal with sediment build up before it causes problems. Rainwater tanks slowly fill up with sludge over the course of a year. Just leave your tank for 12 months and you’ll probably see an inch or two of sediment sitting at the bottom. This can drastically reduce your water storage capacity and create the perfect environment for nasty bacteria to grow.
Prevent pump seizures through regular exercise. It might be tempting to leave your pump disconnected and unused during winter. But just like muscles, pump seals begin to deteriorate if they aren’t used regularly. Run your pumps once a month regardless of whether you need rainwater. This keeps pumps in working order and ready to go when you actually do need water.
Clean filters before they stop catching the debris they were designed to trap. Most rainwater harvesting filters are physical barriers; some contaminant matter will pass through once your filters are 50% blocked. Leaf guards greatly reduce the workload but don’t expect your filters to stay clear forever. Clean or replace filters annually to maintain peak performance.
Timing is important. Chemical cocktails and household gadgets that promise to keep your water sparkling will be great…until they’re not. Buying chemicals every month is expensive. And when they stop working you’ll still be stuck spending hours cleaning your system with a brush and a hose.
## Monthly Maintenance Checks
**Clean gutters and gutter mesh**: Every month clean out roof gutters and gutter mesh traps (ExcelSHE). If you think your rainwater is clean because you have leaf guards installed then think again. Not only will your leaf guards still require regular cleaning they won’t stop fine dust, soil, and pollen collecting in your gutters.
All that debris and mud washed into your gutters every month doesn’t just affect how much water you collect. It coats whatever rainwater does make it into your tank with fine layers of grime. Clean gutters, once a month.
Clear debris from first flush diverters: Just like your gutters (ExcelSHE). Leaves, sediment, soil, and all manner of creepy crawlies work their way into your first flush diverters. On systems we’ve installed the leafier months of November to February fill them right up. Give them a once over once a month and clear out anything lurking down the bottom.
Flush out wet systems: Do you have wet pipes? Then drain them down (ExcelSHE). These are the pipes that remain full of water between rainfalls. Harmless bacteria flourish in standing water. Flushing your wet system once a month gets rid of stagnant water and prevents foul smells developing.
*I spend most time on gutter maintenance during autumn months and flushing my wet systems after heavy rainfall in winter and spring. *
The Biggest Mistake I Made With Maintenance: Thinking I could leave my system alone. Once rainwater is disappearing into your tanks out of sight, it can be all too easy to forget about it until something goes wrong. Cleaning your gutters once a month takes seconds. Flushing your wet system every month takes minutes. Regular maintenance really can take less time than you think.
## Seasonal Deep Maintenance
This heavy duty maintenance needs doing once every season. Yup, that doesn’t mean once a year. Spring, Summer, Autumn and Winter. Four times a year your rainwater harvesting system requires a little more TLC.
**Spring Rainwater Harvesting Maintenance**
Prepare for Autumn: Checking overwinter damage in Spring and making sure everything is in working order before leaves start to fall. Scour storage tanks if they’ve accumulated sediment over winter. Replace tank covers and ensure tank vents aren’t blocked. Clean UV lamps annually (Graf UK), so April’s the ideal time for first clean of the year.
Replace heavy duty filters: You should really be checking and cleaning your filters (Landscaping Superstore) once every season. If you’ve noticed particularly high contamination during winter rainfalls then consider replacing filters in spring. It’s far better to change them annually before they become a problem.
Test run pumps after winter dormancy: Just in case your rainwater system hasn’t been used all winter it’s always worth having a quick test run of your pump. You’d be surprised how many people realise they’ve got a broken pump after switching to rainwater in spring only to find out they haven’t used it all winter!
**Summer Rainwater Harvesting Maintenance**
Watch your water quality: Summer’s a funny old time for rainwater. We experience longer periods without rainfall which means the water you collect tends to sit around longer. Also, warmer temperatures = faster biological growth. Algae likes light and warm water. Always empty out the water left in your tank after a summer drought and give it a good clean if it smells funny.
Don’t forget about those first flush diverters during heavy rainfall: If you haven’t had a rainfall for weeks, then the first really heavy rainfall is going to carry some serious contamination your way. Make sure those first flush diverters are clean and ready for the onslaught!
**Autumn Rainwater Harvesting Maintenance**
Pressure wash gutter systems: Gutters and downpipes should be professionally cleaned annually (Graf UK). Autumn is the ideal time to book your professional gutter cleaning before the winter weather sets in.
Check for storm damage: Bad weather can move gutter guards askew, damage first flush diverters, and leave water overflowing from gutters. Take a good look around your rainwater harvesting system once Autumn storms have passed. Make a note of anything that needs fixing before next winter.
Inspect tanks annually for debris, damaged covers and proper sealing (Graf UK). Doing this in Autumn gives you time to drain down and clean your tank if necessary.
**Winter Rainwater Harvesting Maintenance**
Insulate your system from freeze damage: Pipe work, tanks, and first flush diverters can all suffer in winter. Drain down any water pipes that have the potential to freeze. Don’t forget to check your drainage points actually drain completely! This is one of the biggest causes of freeze damage.
Run your pumps monthly: Every month run your pumps for a few minutes to prevent seals drying out. You don’t need to use your rainwater every month in winter. Just make sure your pumps are ready to go when you do!
Clean UV lamps six monthly: As part of your winter maintenance, give those UV lamps a good clean (Graf UK). They don’t need replacing as often as filters, so twice a year is perfect.
*I always inspect my system overwinter damage during the Spring. Once the worst of the winter weather is over and before the Autumn rush begins. *
Mistake #5: Never cleaning your rainwater storage tank. Gross, right? I know what you’re thinking. Who spends that long staring into their rainwater storage tank? Me that’s who. Sediment builds up every month in your tank. Microbiology grows. Algae breeds. If you’re lucky you’ll see the sludge left at the bottom of your tank once you drain it down. The reality is that nobody wants to think about what’s lurking at the bottom of their rainwater tank. Until it starts smelling.
## Maintenance Musts & Where To Start
All rainwater harvesting maintenance tasks can be broken down into DIY and Professionals jobs.
Firstly, where to start? If you’re new to rainwater harvesting maintenance start with gutter cleaning. Clean gutters are the most important step to keeping your rainwater harvesting system clean. A staggering amount of contamination bypasses first flush diverters and filters when they should actually be staying out of your rainwater tank.
**Rainwater Harvesting Maintenance: DIY**
* Clean gutters and gutter mesh
Monthly gutters and gutter mesh cleaning is a DIY job (ExcelSHE). Leaf guards are no excuse either.
* Check and clean first flush diverters (ExcelSHE). Yup. Every month.
* Flush out wet systems (ExcelSHE). Again, monthly.
* Clean filters (Landscaping Superstore). Filters need cleaning or replacing once every season.
* Test run pumps (Landscaping Superstore). Annual pump tests should be carried out to ensure optimum performance.
* Wash down tanks (Landscaping Superstore). Empty and scour storage tanks to remove sediment build up.
* Clean UV lamps (Graf UK). 6 monthly cleaning is all it takes to keep your lamps in working order.
**Rainwater Harvesting Maintenance: Leave To The Pros**
* Have gutters and downpipes cleaned annually (Graf UK). I’m saying this twice for a reason. Gutter cleaning is important.
* Pump servicing. (Landscaping Superstore) Pump service is also a big once yearly job. Pumps shouldn’t be interfered with unless you know what your doing.
* Get an electrical contractor to do any electrical work. Did you know that rainwater tanks can actually be used as house batteries? Neither did I until I installed one… Don’t go messing around in your rainwater tank unless you know 100% what you’re doing.
* Attend an accident in your tank at your own risk. You get the picture.
## Rainwater Harvesting Maintenance Checklist
| Maintenance Task | Frequency | DIY/Professional | Estimated Cost | Priority |
|---|---|---|---|---|
| Clean gutters & gutter mesh | Monthly | DIY | £ time | High |
| Clear first flush diverters | Monthly | DIY | £ time | High |
| Flush wet systems | Monthly | DIY | £ time | Medium |
| Wash filters | Every season | DIY | £ time/materials | Medium |
| Test run pumps | Annual | DIY | £ time | Medium |
| Scour tanks | Annual | DIY or Professional | £150-300 | Low |
| Professional gutter clean | Annual | Professional | £70-120 | High |
| Pump service | Annual | Professional | £80-150 | High |
| Professional electrical work | As needed | Professional | Varies | High |
Got questions about how to maintain your rainwater harvesting system? Join the discussion down below.
The information contained on Rainwater Harvesting Hub comes from many years of maintaining rainwater harvesting systems professionally as well as my own personal system. The recommended maintenance schedule is backed up by ([Graf UK](https://www.graf.uk/maintenance-tips-for-rainwater-harvesting-systems/)), ([ExcelSHE](https://excelshe.com/wp-content/uploads/2023/06/Rain-Harvesting-Maintenance-Checklist.pdf)), and ([Landscaping Superstore](https://www.landscapingsuperstore.co.uk/help-and-advice/project-guides/home-growing-plant-care/the-essential-guide-to-maintaining-your-rainwater-tank/)).
Studies in rainwater tank failures have also shown that the majority of breakdowns are caused by a lack of maintenance rather than part failures ([ExcelSHE](https://excelshe.com/wp-content/uploads/2023/06/Rain-Harvesting-Maintenance-Checklist.pdf)). Annual maintenance like gutter cleaning, testing pump operation, and cleaning first flush diverters all have a direct correlation to preventing failures.
(Landscaping Superstore) also mentions that sunlight reaching your rainwater tank can promote algae growth. Cleaning your UV lamp ([Graf UK](https://www.graf.uk/maintenance-tips-for-rainwater-harvesting-systems/)) every six months is also recommended.
Further reading on maintenance.
Here at Rainwater Harvesting Hub we focus mainly on roofs, gutters, and overflows. But did you know that you can harvest rainwater fromgroundsurface runoff too? Find out more about how to harvest rainwater from the ground.
