HSG274 Table 2.1: Monitoring Frequencies for Hot and Cold Water Systems

Table 2.1 of HSG274 Part 2 is one of the most frequently referenced sections in legionella risk management. It sets out the minimum monitoring and inspection frequencies for hot and cold water systems -- the tasks that duty holders must carry out on an ongoing basis to maintain compliance.

This guide provides a clear breakdown of every task, its frequency, and practical notes for assessors.

Why Table 2.1 matters

Table 2.1 is not advisory -- it represents the minimum standard that the HSE expects. During enforcement action, inspectors will look for evidence that monitoring has been carried out at the frequencies specified. Missing or incomplete records are one of the most common findings during HSE investigations.

If you are a duty holder, think of Table 2.1 as your compliance calendar. Every task listed must be carried out, recorded, and reviewed.

Monthly tasks

These tasks should be completed every month:

Temperature monitoring at sentinel outlets

• Check the hot water temperature at the nearest and furthest outlets from each calorifier or water heater
• Hot water should reach 50 degrees C within one minute of running
• Check cold water temperatures at sentinel points
• Cold water should be below 20 degrees C within two minutes of running

TMV checks

• Check the outlet temperature downstream of all thermostatic mixing valves
• Confirm that TMVs are functioning correctly and preventing scalding

Shunt pump / return circuit checks

• Confirm that the hot water return circuit is maintaining temperature
• Check return temperature at the calorifier (should be at least 50 degrees C)

Quarterly tasks

These tasks should be completed every three months:

Temperature monitoring at a representative selection of other outlets

• Beyond the monthly sentinel checks, rotate through remaining outlets quarterly
• The goal is that every outlet is checked at least once per year

Shower head and hose inspection

• Inspect showers for evidence of scale, biofilm, or deterioration
• Clean or replace shower heads and hoses as required
• Flexible hoses are a particular risk area for biofilm

Infrequently used outlet review

• Review the list of infrequently used outlets
• Confirm that flushing regimes are being followed
• Update the list if building use has changed

Six-monthly tasks

Cold water storage tank inspection

• Visually inspect cold water storage tanks
• Check that lids are secure, intact, and insect-proof
• Check for evidence of contamination, debris, or biological growth
• Confirm that overflow and warning pipes are properly screened
• Check the water temperature in the tank

Calorifier inspection

• Check the calorifier for correct operation
• Confirm storage temperature is at or above 60 degrees C
• Check for signs of scale or corrosion
• Drain a sample from the bottom drain valve to check for sediment

Annual tasks

Full system review

• Review the entire water system against the schematic
• Confirm that the schematic is accurate and up to date
• Identify any changes to the system since the last review

Calorifier drain-down and inspection

• Drain the calorifier and inspect internally where possible
• Check the sacrificial anode (if fitted)
• Check for sediment accumulation at the base

Cold water tank clean

• Arrange cleaning of cold water storage tanks if inspection shows it is needed
• HSG274 recommends cleaning at least annually or as indicated by inspection

Risk assessment review

• Review the legionella risk assessment
• Update it if there have been changes to the system, building use, or occupancy
• ACOP L8 requires regular review -- most organisations adopt a two-year cycle, but annual review is good practice

Monitoring programme review

• Review the effectiveness of the monitoring programme
• Check whether the frequency and scope of monitoring remain appropriate
• Update the programme if risk conditions have changed

Recording and documentation

Table 2.1 is only useful if the results are recorded properly. For each monitoring task, records should include:

• Date and time of the check
• Location (specific outlet, tank, or equipment)
• Result (temperature reading, visual condition, pass/fail)
• Name of the person carrying out the check
• Any actions taken as a result of the check

Records should be kept for at least five years and be available for inspection by the HSE, the duty holder, and the responsible person.

Common failures

The most common failings around Table 2.1 compliance are:

1. Incomplete records -- checks carried out but not recorded, or records missing key details
2. Missed outlets -- not rotating through all outlets over the course of the year
3. No review -- monitoring data collected but never reviewed or acted upon
4. TMV neglect -- TMVs not checked monthly, or not serviced according to manufacturer guidance
5. Tank inspections skipped -- cold water tanks not inspected six-monthly, particularly in buildings with difficult access

L8Pro helps assessors identify these gaps during the risk assessment and generates recommendations that reference the specific Table 2.1 requirements.

Key takeaways

• Table 2.1 sets the minimum monitoring frequencies -- not the maximum
• Monthly temperature checks at sentinel outlets are the foundation of ongoing compliance
• Every monitoring task must be recorded with sufficient detail
• Quarterly, six-monthly, and annual tasks are easily overlooked but equally important
• Records must be retained for at least five years
• The monitoring programme itself should be reviewed annually