Network Health checklist
Use this network health checklist to understand and control the risks to your network:
| Hazard | Hazard Description | Risk | Control |
| Long pipe lengths. | Poor turnover: Water remains dormant for long periods, allowing it to stagnate. Elevated metals concentrations: Where pipes are metal, long exposure of water to the pipes may result in dissolution of metals into the water. | Objectionable taste odour or appearance bacterial growth. Exceedance of metals standards (for instance; lead, copper, nickel). | Regular flushing of twice the capacity of the pipe. Reduce pipe run when possible. Ensure the system is not unnecessarily convoluted or long. |
| Age, condition and material of pipes. | Potential for pipe material or component substances to dissolve (such as lead) or break off into the water (such as iron). | Cloudy water, water with particles, and possible objectionable taste and odour. Potential health effects depending on materials. | Replace or improve the pipes. Flushing in the short term may help, but it could make it potentially worse. |
| Inappropriate location of pipes, vessels and chambers. | Pipes and storage tanks/reservoirs located by waste facilities (latrines, toilets etc) or storage of contaminants such as oil could inadvertently leak into the supply. | Contaminants may enter the supply leading to illness and/or taste, odour, and appearance issues. | Relocate pipes/vessels to a less hazardous location. Ensure tanks, chambers and tanks are in robust condition with protective measures in place, such as bunding around oil storage. Ensure pipes are lined (barrier pipe) or are run in a protective sleeve to prevent chemicals migrating through plastic. |
| Age, condition and material of storage vessels (tanks, reservoir, chambers). | Breakdown of materials into the water, potentially hazardous chemicals. Possible ingress points. | Cloudy water, water with particles, objectionable taste and odour. Risk of decaying animals where they have gained access via holes, cracks etc. | Upgrade or replace the vessel. |
| Contamination via ingress points. | Inappropriate covers on inspection chambers or storage reservoirs or tanks, including loft tanks, will allow ingress of animals, including vermin and insects or encourage algal or bacterial growth | Ingress of land run off (pesticides, industrial pollutants), farm slurry or animal faeces from wildlife or grazing livestock. | Inspection chambers, reservoir and tank roofs must have robust stock proof fencing. Ensure vents have a gauze covering, ensure chamber covers are adequately sealed and raised above the ground where possible. |
| Low or irregular usage/little throughput of water. | Low usage can encourage microbial growth or slime on the pipe walls called biofilms. | Taste, odour, and appearance problems. | Ensure tanks and reservoirs are of a suitable size to ensure regular turnover, ensure the system is not unnecessarily convoluted or long. |
| “Dead spots” in the system (areas of low or no flow such as redundant pipework or dead spots due to poor mixing). | As above. Water remains dormant for long periods, allowing it to stagnate, and this may get pulled back into the main flow of water. | Taste, odour, and appearance problems. | Remove dead legs and dead spots where possible by simplifying the system and ensuring adequate mixing and turnover. |
| Fittings on the system that are unapproved, in poor condition, or inappropriate. | Unapproved materials from fittings products or treatment chemicals can impart chemicals to the water or encourage microbial growth in the system. | Taste, odour, and appearance problems. Potential health issues depending on the circumstances and product. | Products should be replaced with appropriate approved materials and products, according to regulation 5. |
| Back flow risks. | Contaminants get pushed or sucked into the system due to pressure changes due to absence of backflow prevention devices. Possible contamination of the public supply. | Taste, odour, and appearance problems. Potential health issues depending on the circumstances and contaminants. | Ensure appropriate protection devices are installed. Consult local water company. |
| Uncontrolled operator access. | Uncontrolled use of valve or hydrant operation. | Inadvertent stirring up of sediment in the system leading to taste, odour or appearance issues. Connection of apparatus with inadequate backflow protection. | Restrict access to use of valves and hydrants. Document a procedure for their operation by approved personnel. |
| Untrained operator access. | Contamination of the supply by work conducted by an untrained individual. | Contaminants may enter the supply leading to illness and/or taste, odour, and appearance issues. | Require operators to hold a ‘blue card’ (or equivalent) under the National Water Hygiene scheme to demonstrate adherence to good hygiene practices. For reference, UK water companies require individuals entering or working on clean water sites to hold a valid blue card. |