There are two questions to be addressed in this article, the second follows on from the first: The value of a rainwater harvesting system is directly related to how effective it is at reducing water bills and minimising environmental impact. In this article we will explain how a residential rainwater harvesting system should work and the returns that can be expected by end users.
Understanding Rainwater Collection
With over 100 days a year of rain on average, houses in the UK can use this natural resource to their advantage. However, not every type of property is suited to rainwater harvesting, and some areas and property configurations will yield better results than others.
The effectiveness of a residential rainwater harvesting system depends on numerous factors. These include the design and incline of the roof, the positioning of downpipes, and the total surface area of the roof (the catchment area). Rain is channelled from the catchment area through the downpipes into a storage tank, via one or more filters at the entry point to remove dirt and debris.
The design of a rainwater harvesting system varies from property to property, but each shares the following features in common:
- There is a rain catchment area, which is usually the roof of the house and/or that of an outbuilding.
- There is a system that takes the collected water from the catchment area to the storage tank, via a filter. This system may include gutters and down pipes. In a large or complex system, there may be several pipes that collect water from different sources and move it into a shared storage tank.
- There is a storage reservoir in the form of a water butt, or a tank, which may be stored above or below ground. This is linked to utilities in the home by means of a pump and network of pipes.
Effectiveness & Cost
From here we move on to the question of effectiveness: how much water can a collection system harvest and how much does it cost to do so?
The amount of rainwater that can be collected depends on the area of roof and the rainfall in that location. An average sized free standing water butt, such as those used to collect rain for garden use, typically hold 100L – 300L of water. Larger capacity above-ground tanks can hold up to 6000L for domestic systems, with larger tanks for commercial systems available up to 30,000 litres. Underground storage tanks also vary in size, the average capacity for a domestic system being 2000 to 5000 L, and up to 100,000 litres or more for commercial systems.
The cost of the equipment for an above-ground rainwater harvesting system for garden use is about £800-£1500. A below ground domestic system will cost more, in the region of £2000-£3000. Installation costs will vary widely depending on ground conditions, access etc. and whether this is for a new build, or a retro-fit system for an existing house.
Once in place, end-users can start seeing the benefits straightaway. Good quality systems require very little maintenance, and a householder can expect to save anything from 40% upwards on their annual water bills depending on water usage and the size of the property.
The monetary value of this will of course vary from one property to another, depending on location and who the water supplier is. Though, with water prices increasing annually, the savings will improve over time. However, as with other technologies such as solar power, heat pumps etc. quick returns are rarely gained whereas taking a long term approach will yield continuing benefits.
Effective Rainwater Harvesting Solutions
At Rainharvesting Systems we supply cost-effective, high quality rainwater collection systems for domestic and commercial properties of all sizes. To talk about your requirements or for a bespoke quote, please call 01452 772000, or send a sales enquiry to .
For more information, take a look at our Guide To Rain Water Harvesting Systems, a free e-book that can be downloaded by clicking here.
