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What are the different types of rainwater harvesting systems?

What are the different types of rainwater harvesting systems?

Most of us know the benefits of installing a rainwater harvesting system in our gardens but would like to know more about what types would suit their home best.  There are a few types of rainwater harvesting systems that are used domestically and commercially so depending on your needs, one of these will suit you. Which system you pick completely depends on your needs and space available, after reading this article you should be able to pick a system that’s perfect for you.


Types of rainwater harvesting systems


Water butts


The most common and easy to install system is a water butt. Water is collected from the guttering and fed straight into the tank or water butt. This water is mainly used for small garden jobs such as watering your garden or washing cars and can collect anything from 50L to 1,000L. A high capacity water tank is good for farms, stables and riding schools that need a high volume of water to complete jobs such as washdown and pressure washing.


Anything under 1,000L is fine for a domestic property in an area that has high rainfall (Scotland, Wales etc) and only needs water for smaller projects such as gardening. The south of England has lower rainfall and only requires a water butt of roughly 600L or less depending on how often water is used.


Direct-pumped (submersible)


The most common professional system, a submersible direct-pumped system can be used in domestic properties. This system can pump directly to toilets cisterns and washing machines to really help with water bills and usage. These systems only take from mains water when the tank is running dry to ensure the safe running of appliances.


The size of tank used in these installations range from 1,000 Ltr to 22,000Ltr depending on what you are using the water for and the size of the roof of the property. This system usually uses an underground tank, which arrives ready to install and is put underground in a shallow hole. Underground tanks are great if you have limited space or want to hide your system. The pump is inside the tank and water is filtered before entering the property.


Direct-pumped (suction)


This system does not have the pump inside the tank but is inside a control unit inside your house or business unit. These also use backup from the mains supply so there will always be a feed of water.


These pumps can be added to an above ground or under ground tank so are perfect if you want to start bringing water into your outlets indoors and already have a large capacity tank installed.


Indirect gravity


In this system, harvested water is first pumped to a header tank (high level) and then supplies outlets using gravity, not a pump. The pump only works when the header tank needs more water from the harvesting tank. In addition, the header tank is filled by mains water when the main harvesting tank is empty, instead of mains supplying the harvesting tank.


Indirect pumped


This system is the same as indirect gravity as in there is a header tank and a main harvesting tank, but it does not use gravity to pump water around the building so the header tank can be on the ground. Booster pumps are used to ferry water around doesn’t use mains water to fill up the underground tank, much like the indirect gravity system. This system is brilliant if you need a tailored system to fit your needs as booster pumps can be adjusted to fit the flow and pressure requirements of the building.


Gravity only


One of the rarest systems is a gravity only system as it does not use pumps to feed the outlets and relies on a tank being high up on an outside wall. The tank must be higher than the outlets it needs to supply but still below the guttering which can make it difficult for a domestic installation. This is a very energy efficient option as it relies on the power of gravity to feed outlets.


4 Steps to Rainwater Harvesting at Home


The components of a rainwater harvesting system




These keep water clean, filtered and take away any sediment/leaves and twigs. For large roof sizes you will need more complex filters as more water is collected.


Storage tanks


These can be either over ground or underground and come in a range of capacities. Tanks can be linked together and are sometimes fitted with calmed inlets (stops sediment build up) and overflow units which stop back-flow when they fill up.




All direct systems need a pump to bring the water from the tank to the outlets. What type of pump you choose as part of your system depends on the size of your tanks and requirements. Bear in mind that booster pumps may need to be used if there is a long distance between tank and the destination.


Mains water top-up unit


Sometimes your system will need a top-up from the mains supply. This must be added in line with UK water regulations so familiarise yourself with the laws before installing a system.


To find out more about bespoke rainwater harvesting systems, either ring us on 01462 429758 (Monday-Friday 9-5:30pm) or email [email protected]. See our range and see how you can save money and water on Rainwater Solutions.



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