Greywater Recycling Regulations
Current UK regulations on the management of greywater are provided within:
Approved Document H: drainage and waste disposal
WRAS Information and guidance note 09 02 04: Reclaimed Water systems
The following is taken direct from the guidance note above and contains many answers to queries were regularly receive:
General tips on reclaimed water uses and treatment
9.1 If greywater is to be used for irrigation, apply it direct to soil and not through a sprinkler or method that would allow contact with above ground portions of plants. Avoid aerosol generation, particularly in enclosed spaces.
9.2 Do not apply greywater to crops, which are eaten uncooked.
9.3 Do not apply greywater to plants, which thrive only in acid soil.
9.4 Do not apply greywater to seedlings or young plants, a better use is to well established plants, dispersing over a wide area and alternating with fresh or rainwater, as this avoids build up in the soil or roots of residues eg. sodium.
9.5 Remember that when demand is low (eg.seasonal irrigation), facilities to divert excess greywater or rainwater to sewer or septic systems will be required.
9.6 If greywater is used directly in garden ponds, it will encourage the development of algae and in excess this may cause the pond to deoxygenate and produce offensive odours and harm to pond life. An arrangement of a separate greywater pond, yielding algae for duck or fish food, should be considered.
9.7 If organic solvents are used in the premises, care must be taken to prevent these from entering water cisterns by dissolution from the air
9.8 Design of reclaimed water systems must be based on the amount of greywater or rainwater that will be collected. About two thirds of domestic waste water is greywater. Filters and chemical additives, including disinfectants, must be sized and dosed to deal with the volumes that will be produced as well as the seasonal variations.
9.9 Basic treatment involves the use of settlement tanks and filtration. These measures are important for the control of micro-organisms, as well as the appearance of the water and the functionality of the system. The addition of disinfectant to a reclaimed water system, which lacks adequate filtration will be ineffective and may be hazardous.
9.10 Chlorine and other treatment chemicals can be hazardous. Care must be taken in their delivery, storage and dosing. Warning notices and safety procedures are essential. Do not apply or store chemicals in unventilated areas such as basements and lofts.
9.11 Filters made from natural cellulosic materials will biodegrade and this will eventually cause their failure.
9.12 When sizing tanks make allowance for residues which build up over time. The design should promote settlement of solids to the bottom. Inlets and draw o‑ points should be located to avoid disturbing bottom sediments. Tanks will need periodic cleaning by pumping out sludge, the disposal of which needs to be planned for.
9.13 Filters should incorporate a perforated plate or some other device to distribute the water evenly over the top, a funnel in the bottom to assist water to the drain pipe, a cover and a vent.
9.14 If using household disinfectants based on bleach (chlorine), iodine or bromine, do not use a type, which contains a colouring agent or dye. Useful advice about disinfectants is issued for the treatment and management of swimming pools and spas published by the Swimming Pool and Allied Trades Association (SPATA).
