Point of use (POU) treatment is a generic term that refers to the process by which water is made wholesome at one or more designated points within a premise. This differs from “whole supply treatment” which provides wholesome at all points of consumption on a supply where it is used for any domestic purposes, and or where it is used in a commercial way, for example a food preparation operation. This guidance is primarily aimed at local authorities who are the regulators of private water supplies. Others, notably private supply owners and users, may also find this information helpful. Its purpose is to the explain the suitability of point use (POU) devices in the context of regulatory requirements.
Point of use products
All POU treatment devices are fitted within a property on the supply pipe, usually just prior to a tap that is intended for drinking water. Often this is the only tap in a building or on a supply that is designated as such. Although mainly installed to make water safe to consume at specific points, POU devices are also sometimes installed for aesthetic purposes alone, for reasons of personal preference and acceptability. Consumer acceptability in terms of taste and odour nevertheless forms part of the criteria for water to be wholesome. Water that is not acceptable to the consumer for these parameters is therefore considered unwholesome.
Various POU treatment products are available. They employ different forms of technology to remove, reduce or deactivate chemical and or microbiological contaminants to make water wholesome, and fit for consumption at a tap.
The type of product used must be suitable and adequately control any assessed risk. They must also be made of materials suitable for contact with potable water. UV units for example, are installed to deactivate pathogens and other microorganisms at the designated tap where the water is used for drinking, cooking, and food preparation. In public and commercial buildings that have a private supply designated points/taps are often labelled as “drinking water,” to differentiate them from those that are not. This arrangement is not ideal, as labels can be lost, overlooked, ignored, or the water inadvertently consumed by children or those with reading disabilities, so increasing the risk to these consumers.
Point of use treatments as control measures
The Inspectorate advises whole supply treatment in preference to POU wherever possible, and without exception where a private water supply is being used as part of a commercial and or public activity.
POU treatment is often favoured by owners and users of private water supplies because it may be less expensive than whole supply treatment. Despite the financial benefits, this arrangement may present uncontrolled risks at taps where there is no POU treatment.
The suitability of POU treatment on any supply must always be determined on a case-by-case risk basis and must take account of the vulnerability of those likely to use it. In any situation the installation of a POU device must not compromise human health at any point on a supply where the water is used for one or more domestic purpose.
In all cases, appropriate whole supply treatment should be the first consideration as this will ensure (if properly maintained) that a safe wholesome water is available at all points of the supply where it is used for a range of domestic purposes. This also includes where water is being used commercially for the manufacture, processing or preservation of products and substances intended for human consumption.
If a supply to a dwelling is aesthetically unwholesome, but safe to consume for all domestic purposes, the local authority is not obliged to enforce but has discretionary powers under section 80 of The Water Industry Act 1991 to do so where it is considered appropriate. For example, where the water is being used as part of a commercial or public activity. This is because users may be transient, unsuspecting, vulnerable, or less inclined to consume water that is aesthetically unacceptable to them. As mentioned above, in these cases, the Inspectorate would advise whole supply treatment wherever feasible.