Greywater Recycling

The objective of this project is to test out some of the designs and plans for greywater recycling in our current home.

Greywater Collection

The focus of this project has been in using grey water from the main bathroom in our current house. The main reason for this focus is because this is where most of the grey water is generated in our current home. The main bathroom is also conveniently located along the back of our house.

Initially, we are using a Draper hand siphon to get water out of the bath and into a storage tank.

This project also aims to connect directly into the bathroom plumbing to ensure water is collected from both the bath and the shower, with no effort.

Greywater Storage

Greywater should not be stored long term because it has bacterial content and is usually warm water. A temporary storage tank is used to simplify further distribution. When using a siphon, the rate of flow is not high enough to directly feed sprinklers, etc. It can take 10 to 15 minutes to empty a bath and you don't want to spend that much time each day putting water on the garden.

A storage tank allows you to time shift the distribution by allowing collection throughout the day and to then quickly distribute the water using automated or other simple distribution methods.

Ecosure 350l water tankEcosure 350l water tank
Ecosure 350L water tank
We are using a 350 litre tank and we have chosen this size because it is easily big enough to hold all the water we would want to collect in a typical day. We have chosen a tank that is sandstone in colour to help it blend into the house and make it less noticable from our garden.

All water fed into the tank is filtered using a fine, stainless-steel mesh filter. This removes larger particles and hair.

Despite using a fairly large storage tank, we have to assume that it could get filled up and that we will need an overflow pipe, into the main drainage system.

Greywater Distribution

1 inch BSP tap
Our tank has a 1" BSP outlet near the bottom of the tank. Into this we have attached a large tap, with a brass fitting to accept the standard garden hose push-on connectors. This provides the flexibility to connect many things to the water tank but it does reduce the water output flow slightly.

To boost the pressure of the water leaving the tanks, we are using a 12V in-line Whale pump. This provides enough pressure to use hoses, sprinklers, etc. and greatly reduces the time taken to empty the tank onto the garden.

ShurFlo inline water filter
To stop the pump clogging up with debris, the pump is fed through a filter. We have used a ShurFlo inline filter designed for use in boats and caravans as this doesn't restrict the flow.


2011 has been a particularly dry summer in East Anglia so far. Greywater is the only reason our lawn is still alive and our garden is looking very green.


Using a hand siphon with a standard snap-on hose connector simplifies the emptying of the bath but requires the bath plug to be left closed after bath. It also means having a pipe left dangling from the bathroom window, so that the window can be shut when needed.

We initially used an 8mm clear plastic tube down to the storage tank and it can take a while to empty a bath this way. A pipe with a bigger bore would speed this up but this limiting factor is the connectors on the hand siphon pump.

Tapping directly into the existing bath waste pipe would be much more convenient and a faster way to collect the used bath water. This is a fairly permanent modification though and it requires the drainage to be resolved before attempt to do it.


Even with it being a nice subtle colour, there is no easy way to hide a 350 litre water tank. In a new build, something like this could be designed in and hidden from view though. It would probably make sense to have it in a storage area next to recycling bins, etc.


The 1" BSP outlet is inconvenient. There are limited taps available to fit this size of outlet as it is primarily for industrustrial and agricultural irrigation systems. The plus side is that it provides high water flow. We managed to find suitable taps and fittings on eBay and at places like Screwfix though.

Further Reading

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