Non-wholesome water
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To the south of this monitoring bore hole in Oareborough Lane, West Berkshire, is an old quarry that has been used as a landfill. It is surrounded by a series of observation wells for groundwater sampling. |
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[edit] Introduction
Non-wholesome water is water that moves through commercial or industrial water distribution systems but does not comply with the requirements of regulations made under Section 67 (Standards of wholesomeness) of the Water Industry Act 1991. The regulations made under this Section are, for England, the Private Water Supplies Regulations 2009 (SI 2009/3101), for Wales the Private Water Supplied (Wales) Regulations (SI 2010/66) and for England the Water Supply (Water Quality) Regulations 2000 (SI 2000/3184 as amended), and, for Wales, the Water Supply (Water Quality) Regulations 2001 (SI 2001/3911 as amended). Water that meets these requirements is referred to as wholesome water.
[edit] Sources
Non-wholesome water may come from sources including:
- Industrial processes (such as treated wastewater from sewage treatment plants).
- Groundwater abstraction (from wells, bore holes or springs).
- Surface water (from rivers, streams, ponds and so on).
- Water reuse systems such as rainwater harvesting or treated greywater (from baths, basins and showers).
[edit] Usage
Non-wholesome water can be used as an alternative to mains water in applications that do not require wholesome water, such as:
- Toilet flushing. Poor quality of non-wholesome water is an acceptable alternative, since there is little likelihood of dangerous human contact.
- Landscaping. For general purposes, non-wholesome water is suitable for most irrigation purposes, other than when it could be used on vegetation that is intended for consumption.
- Laundry. Non-wholesome water that has been properly treated (so it does not contain any potentially problematic microorganisms) can be suitable for laundry.
It is not advisable to use poor quality non-wholesome water in situations where the stream - or even spray from the stream - could come into contact with people, animals, birds, edible vegetation and so on.
[edit] Safety issues
Guidelines for the use of non-wholesome water can be found in Approved Document G of the Building Regulations.
If non-wholesome water is being considered as an alternative source, the reliability of its delivery should be evaluated for possible risks. Its treatment system should also be designed to minimise the impact on water quality due to:
- Failure of any components.
- Failure to undertake any necessary maintenance.
- Power failure.
- Other measures identified in a risk assessment.
An alternative supply to non-wholesome water should be sourced if there is a question regarding reliability. If a wholesome supply is used for backup, there must be no opportunity for contamination of the wholesome water supply by the non-wholesome source.
Non-wholesome water must not be inadvertently supplied in place of wholesome water and it should not be permitted to contaminate wholesome water systems, for example, by misconnection. Pipes carrying non-wholesome water should be marked clearly, using different types of pipework to avoid misconnection. Colour coding can also be useful, as long as non-wholesome water is not transported in blue pipes, since this colour is typically associated with wholesome water mains.
Marking is important if distinctions between pipe types are covered by insulation. According to guidance from NBS, non-wholesome pipework labels inside dwellings should be:
- Green in accordance with BS 4800:1989 colour 12 D 45.
- Not less than 100mm long.
- Marked 'NON-WHOLESOME WATER' in black letters not less than 5mm high (note that other guides recommend different wording, such as 'Reclaimed water', 'Non-potable water' or 'Rainwater' – any term may be used provided that the message is clear)
- Self-adhesive, wrap-around or mechanically fixed to the pipe at intervals not greater than 500mm and at key connection points.
For large-scale reclaimed water pipelines (in commercial/industrial settings such as multi-occupancy buildings, schools, offices) and where the pipes are insulated, marking in accordance with the principles of BS1710: Identification of pipelines should be used. Points of use should also be clearly identified by a green and black label stating 'non-wholesome water' or by a prohibition sign stating that the water comes from an alternative system.
[edit] Related articles on Designing Buildings
- Approved Document G.
- Black water.
- Do our water quality standards demonstrate to the public that their water supply is clean?
- Foul water.
- Greywater.
- Mains water.
- Potable water.
- Rainwater harvesting.
- Reclaimed water.
- Types of water.
- Water quality.
[edit] External resources
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