Thursday 26 February 2009

British Standard for Rainwater Harvesting Systems


The recent publication of British Standard 8515 for rainwater harvesting systems, available via http://www.bsigroup.com/, establishes for the first time a yardstick against which systems being supplied in the UK can be measured.

Harvesting rainwater to supply household needs is one of the oldest and most durable forms of supplying water worldwide, although until recently practiced in the UK mainly in the context of garden irrigation, following the introduction by the Victorians of mains-supplied water.

Due to modern lifestyles and population growth, however, UK mains water supplies are now coming under varying degrees of stress – particularly in England south of the Humber where the stress is generally severe (see Environment Agency map).

This is reflected in the mains water consumption requirements set out in the Code for Sustainable homes, and commercial equivalents such as BREEAM assessments. Up to a point, these requirements can be met by economising on water use, but if lifestyle (baths and showers etc) is not to be compromised then substituting recycled water for mains water becomes necessary.

The easiest and most cost-effective way of doing this is to use harvested rainwater instead of mains water for non-potable uses such as toilet-flushing, clothes washing machines, car washing and irrigation. This reduces mains water consumption by around 50% in the home and by more than 80% in any building that combines a large roof with a high demand for non-potable water.

BS 8515 now sets the standard for how systems as a whole (see schematic diagram) and components within the system should function. Very simply, the aim is to route the rainwater falling on the roof to a storage tank, filtering it beforehand to remove any solid impurities. When needed, the water is then pumped (directly or via a header tank) to its point of use via pipework dedicated to non-potable water.

From the users perspective, using rainwater in this way is indistinguishable from using the normal mains supply, with the associated controls automatically controlling all functions and ensuring, using a mains water backup when needed during prolonged dry spell, continuity of supply.

Wednesday 18 February 2009

Water Charges set for inflation busting rises

Introduction

Previously agreed water charge increases come in to affect from 1st April 2009. This was agreed sometime ago and it is 1.1% above the latest inflation rate, currently 3%. Ofwat have suggested that this should increase the average water bill by £13 per year. Some water companies such as South West Water are increasing their prices by as little as 0.9%, but they do currently have one of the highest tariffs.

More on the way

Ofwat are currently developing the pricing strategy for the years 2010 to 2015. During uncertain economic times, clearly this is a very difficult balancing act.

Reasons for the rise

There are a number of factors which have been considered in determining the level of money needed to improve or maintain the level of service. We have been very fortunate in the UK that we developed a world leading water network, but this pioneering period has left the UK with an aging network of both water supplies and sewerage.
There is also increased demand in certain already over-stretched such as the South East of England. Several articles have suggested that this area has less water per head than parts of Africa and this highlights the need to maintain the network. For some years now, we have heard of massive leak rates directly resulting from old pipes.

What else can be done?

Clearly investment is needed and will always be, but this must go hand in hand with other water measures. The Code for Sustainable Homes tackles this issue for new-build domestic homes, but there is little incentive to make water saving measures for the current housing stock. New-build accounts for maybe 1%.
Individuals can take steps to reduce their expenditure on water, some of these are listed below:

1) Aerated taps
2) Aerated shower heads
3) Smaller baths or filled to a minimum
4) Rainwater harvesting (suitable for times of renovation or a simple garden system)
5) Displacement of WC cistern volume with a brick or bottle filled with stones.

There are plenty more ways to reduce water in the home. But obviously, should any of the above measures be taken, the property should be metered and not on a rates or fixed charging structure