With the climate changing and summers getting drier, using a hosepipe to water your garden isn’t sustainable. Sometimes, hosepipes even get banned during dry periods. So having a water tank to collect rainwater to water your garden (as long as the weather isn’t too dry!) makes a lot of sense.
A water tank connected to your roof will collect all the rainwater that would normally go down your downpipe. This free water can then be used to irrigate your garden, helping you preserve a valuable natural resource, saving money on water bills and keeping your garden looking green and beautiful.
The first thing you need to do is decide if a water tank is the right thing for you. Your roof is your rainfall collection area. The bigger your roof, the more water you will be able to collect. But there is no point installing a water collection tank if you have a flat roof or a low pitched roof, as you’re unlikely to collect much water at all.
Next, you need to decide on the right size for your rainwater harvesting tank. You want to be sure it will be able to collect enough water, but you don’t want it so big that it dominates your garden. Tanks for Everything stocks tanks from 150 litres, suitable for domestic and garden use, right up to 30,000 litres suitable for commercial garden and agriculture uses.
The size of tank you’ll need is based on how much water you will use and how much you might collect in a particular season. A water tank that is smaller may look nicer in your garden, but could result in running out of water sooner or not being able to stores enough rainwater when it falls.
We all know that it rains a lot in the UK, but it definitely rains more in some places than it does in others. So, the first thing you need to do is find out how much it rains where you live. Otherwise, there’s no reliable way to work out how much rainwater you could potentially collect and store over the course of a year.
Coming back to the changing climate again, it’s best to use the average data from the last three or four years rather than a longer period for your calculations, because things have changed quite a bit over the last 20 or 30 years.
You also need to know the area of your roof. This is calculated by measuring the length of your roof and multiplying it by the roof slope height (which is not the same as the height of your roof). The roof slope height should be noted in the property documents for your house.
Once you’ve got this information, you will be able to work out how big a tank you need, using this easy calculation: Your roof area (in square metres), multiplied by the annual average rainfall (in millimetres) in your area equals the maximum rain harvesting capacity (in litres).
This will give you some idea of how much water you might be able to collect and store.
You might decide to go for a larger rainwater tank anyway, but this would obviously take up more space and be more expensive.
Another important factor to consider when you are working out the right size of tank is how much water you are going to need for your garden. It might seem obvious, but a bigger garden will need more water than a smaller garden and some plants need a lot more water than others.
To work out how much water you need, you should use a standard watering can of five litres for your calculation. If you use three full watering cans a day on your garden, that is 15 litres. If you can expect a maximum of 14 consecutive dry days, you need to store enough water to last 14 days ie 14 days multiplied by 15 litres equals 210 litres. This would be your minimum tank size.
The next thing to consider is the shape of the tank. Rainwater tanks come in two basic shapes – vertical (cylindrical) or slimline. The majority of tanks are vertical, which work well if space isn’t a problem. Slimline tanks are designed to fit into smaller spaces, for example down narrow walkways on the side of your house.
As water tanks are quite large, most people prefer to place them somewhere out of sight, if that is an option for them (ie if the downpipe is on the side of the house). When choosing your tank, consider the location and be sure you have enough room to access the water from the tank and also carry out any maintenance activities. If you don’t have much space, the location may dictate what shape and size of tank is right for you.
When choosing the right water tank for your garden, the biggest decision is the size of the tank. If you’re unsure which size is right for you, Tanks for Everything can offer you the advice you need, so you can start watering your garden in a more sustainable way and cutting your water bills.
