Treatment Guide

The type and design of any treatment methods used to treat raw water will depend on the properties of the water and the presence and concentrations of any contaminants. It is therefore important to choose equipment, suppliers and consultants carefully. Purchasers of water treatment plant and supplies should:

  • ensure that potential suppliers are aware of the size and nature of the water supply
  • confirm that potential suppliers can supply and install (if required) equipment suitable and approved for use with private water supplies
  • establish whether suppliers can provide references relating to similar projects
  • if practicable inspect other, similar, installations
  • ensure that instructions for use and ongoing management and maintenance requirements of the equipment are provided

When choosing a method of treatment there are a number of questions (see Question Checklist) you should ask an installer to help you verify the suitability of the system for your needs and the capability of the installation company. To aid these discussions the treatment comparison guide provides all the relevant information to ensure the correct system is installed relevant to the type of treatment that is required

Question Checklist

Treatment comparison guide

The multi-barrier approach

The multiple barrier approach is an important concept as it provides the basis for effective treatment and allows each individual process stage to treat water to a suitable quality for subsequent downstream processes. Treatment therefore can consist of a number of stages, with initial pre-treatment by settling or pre-filtration through coarse media, filtration followed by chlorination.

The Inspectorate has developed a manual on treatment for water supplies that outlines the different treatment options that are available for use in private supply systems. The document is also available below to download, as the full manual or by individual sections:

Pollution Assessment

Water Treatment Processes

Appendix A: Glossary

The Inspectorate has also produced additional guidance specifically for the use of UV systems within water supplies systems.

UV systems


One of the most neglected aspects of water supply systems is that of management and maintenance. Often the usual practice being to confront equipment failures and quality issues as they arise, leaving a risk of contaminated water until the problem is remedied. Maintenance should be proactive not reactive and involve a regular, preventive, maintenance programme, which enables early identification of problems. Equipment manufacturers’ maintenance instructions must be followed as a minimum requirement. Simple checks can be used to give forewarning of problems:

  • daily (or more frequent) checks on the operation of disinfection equipment
  • investigate the causes of dirty or discoloured water as it could be due to system failure
  • regular cleaning of filters in line with the manufacturer’s recommendations
  • routine site inspections to check for signs of pollution of the water source
  • structural inspections of the treatment plant, storage tanks and pipework

Maintenance should always be performed by those deemed competent (trained and/or experienced and familiar with the equipment), ideally by the supplier’s servicing contractors. At the time a water treatment system is installed, the supplier should provide training on routine operation and maintenance tasks.

Record Keeping

Any treatment system should come with an appropriate set of instructions for use and operation. This document should also detail any maintenance requirements, including the criteria and regime for the replacement of any products or substances, which must meet the requirements of Regulation 5. Reputable installers should provide a practical instruction and demonstration of the management and maintenance of the system to customers.  The Inspectorate recommends that installers explain the importance of keeping management and maintenance records of any newly installed system to assist with the risk assessment process, required under the regulations.

Back to top