Implementing a Water Hygiene Plan for a London HMO: What It Must Cover

What Is a Water Hygiene Plan?

A water hygiene plan (also called a water safety plan or Legionella control scheme) is the operational document that puts the findings of a Legionella risk assessment into practice. Where the risk assessment identifies the hazards and the risk level, the water hygiene plan sets out the specific control measures, monitoring activities, flushing schedules, and record-keeping requirements that will manage those risks. For an HMO with a stored water system, a water hygiene plan is essential; for a combi boiler system assessed as low risk, a simpler document recording the control measures in place may suffice.

Temperature Control Records

The primary Legionella control measure in a domestic water system is temperature. The water hygiene plan must specify the required temperatures for the system: hot water stored at 60 degrees Celsius, distributed at above 50 degrees Celsius, and cold water kept below 20 degrees Celsius at all outlets. The plan should include a monitoring schedule: how often temperatures are checked, how they are measured, who is responsible, and where the records are kept. For an HMO, temperature monitoring should be carried out at least annually as part of the Legionella re-assessment, and immediately following any change to the water system or any period of low occupancy.

Flushing Schedule

Infrequently used outlets are one of the most common Legionella risk factors in HMO properties. The water hygiene plan must identify all outlets that are infrequently used — spare bathrooms, en-suites in rooms that may be temporarily vacant, ground floor WC taps that are rarely used — and specify a weekly flushing regime. The flushing procedure involves running all taps and showers for a minimum of two minutes to purge the branch pipe and outlet of any stagnant water.

The flushing schedule should identify the responsible person for each outlet. In a managed HMO where the landlord or property manager has regular access, they can carry out the flushing programme directly. In a fully tenanted HMO, the tenants can be asked to flush infrequently used outlets as part of their tenancy agreement, but the landlord retains ultimate responsibility and should verify that the flushing is being carried out. Monthly records of the flushing programme should be kept and retained for at least two years.

Showerhead Maintenance

Showerheads should be descaled and cleaned at least every three months in an HMO, or more frequently where water hardness is high. London is a hard water area — typical hardness levels in London Water supply areas are in the range of 200 to 350 milligrams per litre as calcium carbonate, which is classified as "very hard." At these hardness levels, scale accumulates rapidly on showerheads, taps, and within pipe runs. The water hygiene plan should specify the showerhead cleaning schedule, the method (descaling solution or physical replacement), and who is responsible.

Void Period Procedures

The water hygiene plan must include specific procedures for managing the water system during void periods. When a room in an HMO becomes vacant but the rest of the property remains occupied, the outlets in the vacant room should be added to the weekly flushing schedule. If the entire HMO is vacated, the system should be either flushed weekly or drained, depending on the expected duration of the void. Before re-letting after any void period, the plan should specify the pre-occupation flush procedure, the temperature checks, and the inspection of showerheads and tank covers that must be completed before the new tenant moves in.

Contractor Control

Any work on the water system by a plumber or contractor must be coordinated through the water hygiene plan. After any plumbing work — particularly work involving opening up pipework, draining down the system, or modifying the layout — the section of the system that has been worked on should be disinfected and flushed before the system is returned to normal use. The water hygiene plan should include a section on contractor control, requiring that any works affecting the water system are notified to the responsible person and that post-works flushing and documentation are completed.

Record Keeping

The water hygiene plan must generate a set of records that demonstrate active management of the Legionella risk. These records include: temperature monitoring logs; flushing records; showerhead maintenance records; void period management records; and records of any works carried out on the water system. These records should be retained for a minimum of five years. For HMO licensing purposes, the records may be requested by the local authority as evidence of active water hygiene management, particularly where a Legionella risk assessment has been required as a licensing condition.