Capturing rainwater is easy and very affordable. If you have a roof with gutters, your catchment system is almost complete. But the biggest consideration of the project is where and how to store the water you capture. This is not a very complicated decision, providing you consider a few points in our handy checklist:
1. How much water do you want to store?
You can use rainwater for several things, from refreshing the garden to supplementing water inside your home. If you just need water to keep your pot plants going, you won’t require a huge tank. But if you plan to irrigate your lawn or wash cars, you will need more storage space. Another consideration is rainfall: if you get rain very often, your tanks can refill regularly (and don’t need to be big). But if rain is scarce, large tanks are better for stockpiling. This is also a good time to decide how many tanks you may need. You can always add more tanks to the system later, but it’s smart to have an idea beforehand and avoid moving the tanks later.
2. Where will the tanks stand?
Water is heavy: 1 litre is one kilogram. So a 500 litre tank, which isn’t uncommon, will ultimately weigh over half a tonne when it is full. This is enough to crack paving or destroy a raised platform. Thus think about where the tank will go, as it must have decent support underneath (even a stray rock can crack the bottom of a heavy tank). You also want the tank to be in a useful spot: if the stored rainwater is for your garden, the tank shouldn’t be on the other side of your building. But do you have space for it where you need it (and how much space do you have)? Some prefer to hide the tanks, others don’t. You can get very attractive-looking tanks suitable for public display. You can also bury tanks, but those must be designed for it. Finally, you want the tank in a spot where it is easy for pipes or troughs carrying the captured water to reach. So before buying tanks, think about where they will go and then choose an appropriate design.
3. What should the tank be made out of?
Please visit our handy post on the different materials tanks are made from. You can get tanks made from high density plastic, fibreglass, wood, metal, concrete and more. Plastic tanks are the most popular and affordable. Whatever you choose, though, make sure that the tank material has proper UV protection (UV stabilizers) to reduce sun damage, that it is opaque (not transparent) to reduce bacterial growth. Also consider how easy it would be to fix or replace fitments such as taps and pipes.
4. How will it connect to your capture system?
You will direct water from your roof to the tanks, so don’t forget to check they are compatible. Most good tanks have standard plumbing fittings, but still make sure you can confidently connect pipes. Tanks can be modified and new fitments can be added, but it depends on the material. For example, modifying a plastic tank is far easier than cutting holes into fibreglass or metal tanks. Also, think about how you will get the water out: a tap, a pump or some other way?
5. How will you maintain the tank?
A well-maintained tank can last a lifetime and fortunately good rainwater storage tanks are not demanding on maintenance. Still, you want to be able to drain and clean a tank, as well as affect repairs on it when necessary. So keep this in mind when installing the tank: how easy is it to access and drain? Where will the water drain to (perhaps another tank)? Will there be challenges replacing any damaged pipes or fitments? A well-installed tank usually needs very little attention. Still, anticipate that at some point a spot of maintenance will be required. No sense in making it impossible to do.