Rainwater Harvesting systems can look complex and daunting to begin with. They really aren’t, the technology is straight forward and a builder can install the systems using their own ground workers and plumbers.
Here at Rainwater Harvesting Ltd we’re committed to helping you every step of the way.
So here is a brief overview of Rainwater Harvesting. For a more in depth explanation please Click Here.
Rainwater Harvesting is a concept that has been around for thousands of years. The process is to take the rainwater from the roof, down your down pipe and into a storage tank. Whilst the water is traveling from your rooftop it must pass via a filtration system, either built in to the down pipes or better still built into the underground tank.
You then have clean fresh water stored in the underground tank. Please note you do not take the water from the ground i.e driveways or patios due to potentially causing contamination in the water. Also it is not advised especially if you are using the water in the house to collect water that has come from a ‘Green Roof’.
This rainwater can then be used for either toilet flushing, washing machine and anything external like irrigating the garden or washing the car. The rainwater is pumped to the appliances via a pump either directly or via a gravity feed system, we will come to that shortly.
All Rainwater Harvesting Systems should have an overflow device so when your tank fills up and excess water or debris, leaves etc get discharged through the overflow device to a soakaway, watercourse or drainage system.
Within a Rainwater Harvesting System there are certain components that you need to decide which to use.
The first job though is to ask yourselves, what are you going to use the water for?
There are 3 main types of systems. Click on each of the following and a new window will appear and explain each type.
Below Ground Tanks
We will always recommend the below ground tanks especially with a new build, the installation is a lot easier, the quality of water greatly improved and of course there are no space issues.
There are two types of below ground storage tanks. Shallow Dig and Deep Dig.
The Shallow Dig Tanks have developed into the market leading type of tank over the last 5-10 years due to them being easier, quicker to install and they are far more groundwater stable than the deep dig tanks. Currently 98% of our system sales use the Shallow Dig Tank.
Above Ground Tanks
These are normally used in the agricultural market where space isn’t an issue and having a large plastic tank stood against a farm shed or behind an outbuilding is not an issue to the eye.
The quality of the water is not as good but if only being used to water the garden they are suitable.
Click on each of the links below and a pop up window will appear to explain each type of tank.
So hopefully by now you know which type of system you will be needing and will have decided whether a below ground or above ground tank would be best suited for your project.
Now we have to think about the size of the tank!
If you are only using the rainwater for the garden there is no basic formula for calculating how much storage you require. It really is down to how much you want to spend and how long a ‘drought period’ you would like i.e how long between rainfalls. We would normally suggest a minimum size of 3000 litres to make it financially viable.
When it comes to using the rainwater inside the house we use a Tank Size Calculator and we size a tank based on 18-21 days drought protection. We take into the account the number of bedrooms as that will give us our demand ( for toilet flushes and washing machine ) based on maximum occupancy. As a general rule providing the roof area and rainfall is sufficient you could work on the following basis :
1 Bedroom – 1500 Litres
2 Bedroom – 3000 Litres
3 Bedroom – 3000 – 5000 Litres
4 Bedroom – 5000 – 7500 Litres
5 Bedroom – 7500 Litres
In our systems we always recommend where possible to have a submerged pump. There is less strain if you have a pump in the water so all it has to do is push the water out to wherever it is feeding. You will see systems on the market where the pump is within the house and the pump is having to suck the water and then push the water. This can cause flow problems and also cause noise.
The standard pump that we use in our systems is the Hydroforce Series 4 Submersible Pump. It is a pressure sensitive pump so if it is connected directly to the toilet for example, when you flush it will automatically start up and then when the toilet valve closes the pump will automatically stop. This is the same for a garden tap, open the tap, pump automatically starts, close the tap and the pump automatically stops.
The Hydroforce delivers at 3.5 bar when it exits the pump so is more than powerful enough to compare with mains water pressure. If you feel you need to travel larger distances there are other pumps avialable, just ask one of the Sales Team.
Hopefully you now have a good idea of the type of system that you will require for your particular project.
You should know whether it will be used for the garden or the home and garden, and if home and garden whether to use direct feed or a gravity feed system. You’ll know whether to use an above ground or below ground tank and also the size of the tank.
Of course if it is still slightly confusing or you would like to talk through your selection make sure you call one of our team 01733 405111 Option 1 and they will be able to make sure the correct system is specified for you project.
