Water usage and drainage: sustainable solutions

How can water use be monitored?

• Install a water meter wherever possible – real water savings can be achieved when occupiers pay for what they use. Ensure that they are installed correctly and regularly serviced.

How can mains water be saved? 

Consider installing the following:

• Dual-flush or low-flush toilets that can reduce water use by up to 20%, or waterless urinals.

• A water displacement device in older cisterns to reduce capacity.

• Showers are more efficient than baths - they use a third of the water (except for ‘power showers’).

• Spray taps for washbasins - they can save 80% of water use.

• Low-water use fittings which should be as near to the hot-water source as possible to reduce ‘dead legs’ and the consequent waste from running the hot tap until it gives hot water.

• Water-efficient washing machines (both domestic and industrial) and dishwashers.

How can water best be collected and recycled within a building?

• Buildings can be designed to allow recycling of ‘grey’ water (usually from bath, shower and washbasins) for flushing toilets or for assisting plant growth and other low quality uses.
• Rainwater collection can be undertaken at different levels of cost, complexity and saving:
  • Installing a water butt, which takes roof water from a drainpipe, is simple and inexpensive.
  • Collection for flushing the toilet or for use in the washing machine requires storage in tanks and filtering.
  • Collection for drinking and cooking requires filtering and purification (NB. aim to avoid chemicals).
  
  

How should planting schemes be managed?

• Avoid plants requiring large amounts of water. Design for drier summers.
• Water plants with collected rainwater (ideally from outside water butts) or household ‘grey’ water.
• Avoid using mains supplies, hoses or sprinklers.
• Increase ground cover and mulch plants at the start of summer to help retain moisture.
• Water plants in early morning or late evening to reduce evaporation.

How can the risk of local flooding be minimised?

• Avoid hard-surfacing of large areas in favour of soft landscaping (e.g. grass or porous paving) which slows the rate of run-off to watercourses. Consider planting on flat roofed areas (‘green roofs’) if rainwater is not collected for re-use.
• Adopt a sustainable drainage systems (SUDS) approach to surface water drainage. With SUDS, the rate of flow is slowed (through filter strips, swales, and soakaways). This prevents flooding and erosion and spreads peak flows over a longer period. SUDS can also filter out some pollutants (e.g. intercepting oil), provide a local water amenity (e.g. balancing ponds) and have the added benefit of increasing biodiversity on the site.
• If you have concerns about flooding:
  • For main rivers, check the maps on the Environment Agency website - (See Further Resources).
  • For information about other water courses, check with your local council.
• In flood risk areas you may be required to submit an individual flood risk assessment, which should show how the risk for occupants is minimised.

What are the alternatives to traditional methods of treating wastewater/ sewage?

• More natural methods of treating sewage have been adopted in many new developments in the UK and proven to be effective. These include:
  • Use of reed bed or wetland sewage treatment, which can also double up as an attractive wildlife habitat. (NB. Only appropriate for larger, self-contained schemes.)
  • In more urban/ built up areas, or where space is limited, neighbourhood treatment can be achieved through new technologies such as solar aquatic treatment or ‘Living Machines’.
  • Composting toilets and waterless urinals - these use no water and should not smell.