Recent press reports have again highlighted the pressures on national water-supplies and the consequences if steps are not taken now to reduce consumption.
All the main national newspapers have now carried articles outlining the likely effect on national rivers if water continues to be extracted at current rates; within a relatively short number of years substantially reduced summer flow-rates are predicted.
Alongside this scenario, the press have also been reporting that the fitting of water meters is to become mandatory. Water meters are shown to play a useful role in reducing mains water consumption, although some claim that this can have a unfair impact on the poor.
So far, articles such as the above have failed to draw the link between reducing national mains water consumption, and the widespread introduction of rainwater harvesting, which reduce domestic consumption by around 50% without any adverse social and environmental effects.
Use for commercial and industrial applications, this mains water saving can rise to in excess of 80% on any building that combines a large roof, with a high demand for non-potable for applications such as toilet flushing, clothes washing and outside use.
Monday 6 April 2009
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.
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
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
Monday 19 January 2009
Rainwater harvesting tanks: Do they need cleaning?
Introduction
Rainwater harvesting systems are becoming increasingly popular, and the fact the Freerain's early customers have had their tanks installed since 1999. Many people are considering the long term effects and issues concerning older rainwater harvesting systems.
Cleaning?
The general water quality and effectiveness of a rainwater harvesting system is largely dependent on the size of the storage tank installed. Too large and it may never overflow and turn the water over enough. Too small and it doesn't store enough water to be effective and the dwelling/project is reliant on mains water top-up.
Assuming the storage tank has been sized correctly, then it should overflow a few times a year, assuming the system includes a calming inlet and has a suitable pre-tank filter, then the tanks really shouldn't need cleaning. The heavier particles should be removed by the leaf and grit pre-tank filter, the finest particles should float and be skimmed off during overflow. The particles in suspension eventually get sucked up by the submersible pump and are then removed by the inline strainer/carbon filter or whatever has been included on the system.
So a well designed system is very unlikely to need cleaning out, but there is one big assumption, this assumes that only roof water has been sent to the system. Water from hard-standing should not be sent to the rainwater tank, nor should water from a green roof system. Although newer green roof systems do filter the water very well. The overflow from the storage tank should also be protected from backing up. In other words, a well designed system, being used in a normal way, should NEVER need cleaning.
Germany
In Germany rainwater harvesting is about twenty years ahead of the UK and their experience is exactly as described above. Only poorly designed or mis-used systems require major maintenance.
Tuesday 6 January 2009
Roof top rainwater storage, does it work?
If you think of a traditional rainwater harvesting system, in the UK and most of Europe. Then you would probably think of an underground storage tank, a physical filter before storage and a pumping system. We have previously looked at the options for controls and this is broadly two types. The direct pressure system and the header tank system, being fed from the underground tank.
We at Freerain Ltd, are asked quite often about the option of eliminating the underground storage tank and diverting roof water directly into a header tank. On first thought this seems like a good idea, no excavation, no underground tank and maybe even no pump!! All sounds pretty good?
Domestic system, we need storage of around 800-1,000 litres per person to make the rainwater harvesting system effective. So a 4,700 litre system when full would weight around 5 MT!! and take up a considerable amount of space. In order to strengthen the floor, it could be very costly and indeed more than a non-concrete underground tank installation. (as per Freerain tanks). We have also previously discussed the fact that the water should remain dark, cold and not subjected to thermo-cycling (that is rapid heating and cooling). Whereas inside a building it might be. Finally, the overflow from storage would need to be designed to never flood the building at times of heavy rainfall.
Commercial systems are more likely to be specifically designed to take the weight, if underground or above ground outside is not possible. But internal sectional storage tanks do tend to me more expensive and take up valuable space.
Filtering the water prior to the storage tank can sometimes be problematic. A traditional underground system utilises gravity to move the water from the roof, through/across a filter and finally in to a storage tank. The rainwater filter is normally either housed in the tank neck (as with Freerain domestic tanks) or externally for larger commercial systems. So if you want to have a high-level storage tank it must be designed to be able to accommodate any invert drops across the filters and the overflow.
In summary, for domestic projects we wouldn't consider it as a viable option, too much weight or too small amount of water stored. For commercial projects it is always an option, but only if underground or above ground external has been considered and rejected first.
We at Freerain Ltd, are asked quite often about the option of eliminating the underground storage tank and diverting roof water directly into a header tank. On first thought this seems like a good idea, no excavation, no underground tank and maybe even no pump!! All sounds pretty good?
Domestic system, we need storage of around 800-1,000 litres per person to make the rainwater harvesting system effective. So a 4,700 litre system when full would weight around 5 MT!! and take up a considerable amount of space. In order to strengthen the floor, it could be very costly and indeed more than a non-concrete underground tank installation. (as per Freerain tanks). We have also previously discussed the fact that the water should remain dark, cold and not subjected to thermo-cycling (that is rapid heating and cooling). Whereas inside a building it might be. Finally, the overflow from storage would need to be designed to never flood the building at times of heavy rainfall.
Commercial systems are more likely to be specifically designed to take the weight, if underground or above ground outside is not possible. But internal sectional storage tanks do tend to me more expensive and take up valuable space.
Filtering the water prior to the storage tank can sometimes be problematic. A traditional underground system utilises gravity to move the water from the roof, through/across a filter and finally in to a storage tank. The rainwater filter is normally either housed in the tank neck (as with Freerain domestic tanks) or externally for larger commercial systems. So if you want to have a high-level storage tank it must be designed to be able to accommodate any invert drops across the filters and the overflow.
In summary, for domestic projects we wouldn't consider it as a viable option, too much weight or too small amount of water stored. For commercial projects it is always an option, but only if underground or above ground external has been considered and rejected first.
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