Domestic case study

Domestic Rainwater Harvesting Example

On this page there are two different rainwater harvesting examples. The first one is recent, showing our locally produced storage tank and patent pending mechanical header tank with delay action. The second example is from over a decade ago when we were still importing tanks from Germany. It was one of the first systems to be studied and data-logged by the Environment Agency.

Example 1

4 bed house

4-bedroom new-build house
Located in Derbyshire
148M2 roof
5,200 Litre underground system with integrated filter
Fail-safe header tank controls with submersible pump

Estimated mains water savings
106M3 per year

System supplied cost £2,245 + VAT
Estimated installation cost £900-£1,000 (includes direct costs only)

Date supplied 2nd quarter 2011


Example 2

Millennium Green

Site history and introduction

This site was completed by 2001 by our construction company Gusto Construction.

Millennium Green has been studied by many academics. This is one of the first commercially built sites of its type and includes a number of environmentally friendly technologies and techniques. One of which is a rainwater harvesting system fitted to each of the 24 plots.

Plot 7

Specific plot details

Plot 7 is a 4 bedroom detached house with a footprint of 153 M2. Resulting an annual expected collection of 92M3 of water per year.

A 3,500L direct pressure system was installed.

The house was occupied by two adults and two children at the time of the study.


Validated Test Results

A year long study was commissioned to evaluate the effectiveness of the system and this was validated by Severn Trent Water company and the Environment Agency.

Below you will see the results (click on the image to enlarge). The first graph shows the volume in the tank on a daily basis. Note the probe failure during the first month!!! Otherwise this demonstrates that there was rainwater available for the entire year.

The second Graph shows the daily usage in terms of drinking and non-drinking. From this you will see that just under 50% of the total demand was served by the rainwater supply.

Monitoring graph Usage graph

Costs & Considerations

Capital cost of the full system £1990 + VAT

Estimated specific installation cost £450

It should be noted that these prices were correct as of 2000 and the installation cost is based on several systems being installed together.


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