service FAQs

Storage tanks should be inspected on at least an annual basis, and cleaned at a frequency determined by their internal condition. This can be immediately after an inspection if the condition is particularly poor, or within the next 12 months if moderate fouling/debris are seen.

HSG274 Part 2 | paragraph 2.57 and figure 2.12 [p25-26]

Where temperature is used as the primary means of control, hot water should be stored at a minimum of 60 °C and distributed so it reaches a minimum temperature of 55 °C within one minute at outlets.

Cold water services should achieve temperatures below 20 °C within two minutes of operation.

HSG274 Part 2 | paragraph 2.156 [p48]

Hollow tube supports provide an area of no flow within a storage tank, and can provide ideal conditions for harbouring legionella bacteria. These should be replaced with solid supports as soon as possible.

HSG 274 Part 2 | Figure 2.12 | EFA/2013/004 [p26]

HSG274 Part 2 provides guidance on routine disinfection of water systems, and also references BS 8558:2011.

HSG274 Part 2 |  paragraph 2.127 [p42]

Where the risk assessment considers fitting TMVs appropriate, the strainers or filters should be inspected, cleaned, descaled and disinfected annually or on a frequency defined by the risk assessment, taking account of any manufacturers’ recommendations. To maintain protection against scald risk, TMVs require regular routine maintenance carried out by competent individuals in accordance with the manufacturer’s instructions.

HSG 274 – Part 2 |  Table 2.1 [p31-33] and paragraph 2.165 (for healthcare and care homes) [p51]

Where positive legionella samples are identified, the actions will be determined by the respective counts. An action plan should already be outlined in the written control scheme, which should be based on the guidance provided in HSG274 Part 2.

Actions can include resampling the affected location(s), a review of the control measures and risk assessment, disinfection of the services followed by resampling.

HSG 274 Part 2 |  Table 2.2 and Table 2.3 (for healthcare and care homes) [p41 and 51]

Yes. ACoP (Approved Code of Practice) L8 2013 states that a suitable and sufficient assessment must be carried out to identify and assess the risk of exposure to legionella bacteria from work activities and water systems on the premises and any precautionary measures needed. The dutyholder is responsible for ensuring the risk assessment is carried out.

ACoP L8 2013 |  paragraph 28-32 [p11-12]

Where temperature is used as the primary means of control, hot water should be stored (if applicable) at a minimum of 60 °C and distributed so it reaches a minimum temperature of 50 °C within one minute at outlets.

Cold water services should achieve temperatures below 20 °C within two minutes of operation.

HSG274 Part 2 |  paragraph 2.6 [p8]

The national requirements for sodium in drinking water is limited to 200mg Na/l.

The same limits apply to private water supplies.

The Water Supply (Water Quality) Regulations 2016 |  Table B Part II [p38]

HSG274 Part 2 only provides actions for levels greater than 100 cfu/litre. It is therefore considered that any counts below this are acceptable. Our advice is to remain vigilant and monitor for any upward trends.

HSG 274 Part 2 |  Table 2.2 [p41]

Establishing and maintaining a chlorine dioxide residual (as total oxidant) of 0.1 – 0.5 mg/l at an outlet is usually sufficient to control legionella in the preceding pipework.

However, for heavily colonised systems, higher residuals (>0.5mg/l) may be required until the system is brought under control. In this situation, the treated water should not be used for drinking purposes.

HSG274 Part 2 | paragraph 2.93 [p35-36]

Showers present the greatest risk from legionella in a domestic water system, due to their capacity to generate high levels of aerosol. HSG274 stipulates that showers should be dismantled, cleaned and descaled, on a quarterly basis (or as indicated by the rate of fouling or other risk factors, e.g areas with high risk patients). This includes any removable parts such as showerheads and hoses where fitted.

HSG274 Part 2 | Table 2.1 [p32]

Low volume heaters (no greater than 15L) should be capable of achieving peak water temperatures of 50–60 °C (55-60 °C in healthcare premises).

A unit which is not capable of this should only be used where there is a very high turnover or alternative measures are in place, such as biocide treatment.

Temperatures from POU heaters should be checked for compliance on a monthly – six monthly basis, or as indicated by the risk assessment.

HSG274 Part 2 | paragraph 2.69 [p28] and Table 2.1 [p31]

Cooling system water should be tested weekly for microbiological activity, using dip slides (or similar).

The timing of dip slides and other microbial sampling is important. The sampling point should be remote from the biocide dosing point and for biocides, which are applied in a shot dose, sampling should be taken when the residual biocide is at its lowest and ideally performed at the same time each week.

Whilst the number of microorganisms present is important, it is also necessary to monitor any changes in the numbers detected, as this will determine the need for reviewing the control measures.

HSG274 Part 1 | paragraphs 1.121 – 1.122 [p41]

Routine monitoring for the presence of legionella should be undertaken on at least a quarterly basis.

However, more frequent testing may be necessary in other situations, such as the following:

i) To help identify possible sources of the bacteria during outbreaks of legionnaires' disease.

ii) When commissioning a system and establishing a new or modified treatment programme, for which sampling should initially be carried out weekly, and the frequency reviewed when it can be demonstrated that the system is under control.

iii) If a legionella positive sample is found, more frequent samples may be required as part of the review of the system risk assessment, to help establish the source of the contamination and when the system is back under control.

iv) The risk assessment indicates more frequent sampling is required, eg close vicinity of susceptible populations.

HSG274 Part 1 | paragraphs 1.125-1.126 [p43]

It is necessary to inspect parts of a cooling water system regularly to determine the level of cleanliness, the need for cleaning and what cleaning process to use, as simply having a water treatment programme in place will not be sufficient to prevent the fouling that will be caused by airborne contamination.

The frequency of these inspections will vary on the fouling potential and should be determined by the history of fouling in the system and the environment in which the cooling tower is operating. The following timescales can be considered typical for different situations:

i) At least every 3 months for a cooling system in a dirty environment (eg a tower that is prone to process or environmental contamination).

ii) At least twice a year for an air conditioning comfort cooling system.

iii) At least every 12 months for a ‘clean’ industrial application and any others.

HSG 274 Part 1 | paragraphs 1.83-1.84 [p27]

Legionella are more likely to proliferate in water systems that are fouled with deposits and biofilm that can protect the organisms from water treatments and provide nutrients for them to multiply. So maintaining system cleanliness is crucial.

Effective water treatment measures can reduce the rate at which a cooling system becomes fouled, however, an evaporative cooling system will inevitably accumulate airborne dust from the atmosphere and may be subject to contamination originating from the process for which the system provides cooling. It is therefore necessary to take cooling systems out of service periodically for physical, and possibly chemical cleaning, to remove this fouling.

HSG274 Part 1 | paragraphs 1.77–1.78 [p26]

Any actions required are determined by the counts of legionella bacteria detected, and Table 1.10 in HSG274 Part 1 provides guidance in this respect.

To summarise though:

i) Counts up to 100cfu/litre do not require any drastic actions, but a close eye on the control measures should be maintained, and the general bacterial counts should be maintained below 1 x 10⁴ cfu/ml.

i) Counts of >100 – 1000 cfu/litre require a greater review of the control measures, and possibly the adjustment of biocide dosing. Resampling of the system is also necessary.

iii) Counts greater than 1000 cfu/litre or persistent low level results require immediate action. The system should be resampled and a shot dose of biocide should be applied. The entire control programme should be reviewed and corrective actions taken. Further sampling will also be necessary.

HSG274 Part 1 | Table 1.10 [p44]

The pH values for the pool water should be maintained within the range recommended for the disinfectant being used. But a pH value of between 7.2 and 7.4 should be the target when using chlorine-based disinfectants. At levels above this range the free chlorine will not be so effective and accordingly may need to be increased.

The Pool Water Treatment Advisory Group (PWTAG) code of practice 2019 | Section 9.8 [p45]

Swimming pool water should be tested each month to monitor for the presence of potentially harmful microorganisms. Hydrotherapy pools, even those not in a healthcare setting, should be tested weekly.

Tests should also be carried out:

i) Before a pool is used for the first time.

ii) Before it is put back into use, after having been shut down for repairs.

iii) If there are difficulties with the treatment system.

iv) If contamination has been noted.

v) As part of any investigation into possible adverse effects on bathers health.

vi) In the event of adverse results.

More frequent testing may be required if there is a problem or for particularly heavily loaded pools.

The Pool Water Treatment Advisory Group (PWTAG) code of practice 2019 | Section 10 [p47]

The record of the assessment is a living document that must be reviewed to ensure it remains up to date. Arrangements should be made to review the assessment regularly and specifically whenever there is reason to suspect it is no longer valid. An indication of when to review the assessment and what to consider should be recorded. This may result from the following:

i) a change to the water system or its use.

ii) a change to the use of the building where the system is installed.

iii) new information available about risks or control measures.

iv) the results of checks indicating that control measures are no longer effective.

v) changes to key personnel.

vi) a case of legionnaires’ disease/legionellosis associated with the system.

Goodwater’s policy is to undertake a review at least every two years.

ACoP L8 2013 | paragraph 47 [p14]