Rainwater Harvesting: Pressure Tanks Or Pumps?
30 Oct 2017
It is always confusing when you have to decide whether to install a pump or a pressure tank while installing a rainwater collection system. Water pressure (water line pressure) is one of the main issues people in Cork often face when it comes to rainwater harvesting. There are several ways to create water pressure when you turn on the faucet. One is gravity and the other is considering to install a pump. If the gravity does not work on its own, you may need to install a pump.
Pressure tanks versus pumps
1) Pressure tanks have been around for quite a long time and have typically been installed on wells and house rainwater catchment systems. The tanks can hold water for immediate use and there is no lag in turning on the tap, and water comes out from the spout immediately.
2) On the contrary, pressure sensitive pumps or simply pumps are newer and sense the pressure in the water line and turn on whenever there is a pressure drop (make sure that you turn on the faucet).
3) Newest of all are the inline pump controllers. These are completely separate device and not integrated into the pump. Inline pump controllers sense line pressure and help to turn on the pump. They can be easily added to existing installations.
With these three different options, a question naturally arises, that is, which is the best? As per water treatment experts, it depends on the purpose and requirement.
Pumps are commonly used for catchment systems. They are designed to push water rather than pulling it. For that reason, the most appropriate place for the pump is at the same level (elevation) as the water storage tank. The pump can be placed elsewhere, but the efficiency and the life of it can be compromised as the demand to pull increases. The diameter of the supply line from the tank to the pump also affects the pump's performance. This pipe should be a minimum of 1 inch diameter - larger if possible - to reduce strain on the pump.
Changing filters on a regular basis gives you better water flow and reduce work for the pump. It is possible for a dirty filter to impede water flow completely.
Finally, the pressure tank or pump is installed on the basis of line of pressure and the requirement of water.