Sentinel Outlets

the nearest and furthest/last outlets from

hot and cold water cylinders and tanks.

Dead end and dead legs need to be removed

• A dead end- a redundant length of pipe, closed at one end,

through which no water is flowing

• A dead leg - is a pipe leading to an outlet which water flows

but the outlet is un-used or infrequently used.

All need to be removed by cutting them back to the main pipe run

Thermostat mixing valves

• Picture TMVs

these blend hot and cold water to reduce

the temperature where a scald risk is present

Expansion vessels in hot or cold

water systems (not central heating)

• Preferably be flow through

design

• Have a drain valve

– flush through and purge to drain

(HSG274 Pt2 Table 2.1)

• Minimise volume stored

• Should be sited

– in cool areas

– vertically on pipework not

horizontally

Specialised Assisted Baths

• Separate cleaning shower

head system

• Hydro-massage function

• Flexible hoses

• Expansion vessels

• Filters

Other issues to address:

• TMVs should be fitted as close as possible to the point of

use (typically one per outlet);

• Infrequently used outlets should be flushed weekly (includes

short usage and no hot water flowing);

• Shower heads and hoses should be dismantled, cleaned and

descaled or replaced at least quarterly.

• Redundant supply pipework should be cut back as far as

possible to a common supply;

• Replace EPDM (ethylene propylene diene monomer). rubber

hoses with eg. PE (polyethylene), PEX (cross-linked

polyethylene

• Keep water system clean

Monitoring water temperatures for

legionella control

Thermometers needed

Surface temperature probeImmersion temperature probe

Measure the temperature at the hot water tanks

monthly

• hold the surface probe against the pipe

work at the hot water tank outlet

• check the temperature tallies with any

fixed thermometer, if installed.

Measure the temperatures at the sentinel cold water and

hot water outlets monthly

Use the immersion probe to measure the temperature of the

water flowing from the outlet (NB – on hot outlet where TMV is

fitted, this needs to be done on TMV inlet pipe)

•Hot water should measure at least

500C within 1 minute of running

water

• Cold water should measure

less than 200C within 2 minutes

Measure sentinel hot water temperature at inlet to

TMV monthly

Measure at least 500C within 1 minute of running water

Measure the temperatures at the cold water tanks 6

monthly

Incoming water Water in tank

Measure less than 200C

Common failings 1

• No Legionella risk assessment and occupiers are ignorant of the control and monitoring requirements (lack of competence)

• Assessment findings not being implemented

• No schematics or not comprehensive

• Sentinel outlets not identified

• Not measuring hot water temperatures at inlet to TMVs where fitted

• Homes only measure and record hot water temps after tmv’s for scald risk

• Tmv’s fitted too far from outlet

• Not measuring hot water storage temperatures

• Hot water storage thermostats set below 50 degrees C

Common failings 2

• No temperature gauges fitted to hot water outlets and returns (and no one measuring with surface probe)

• Hot water vent pipe overflowing to cold water tank

• Cold water stored above 200C (eg un-insulated cold water tanks located on roofs)

• Cold water tank lids not tight fitting or broken

• Insects screens not fitted to cold water over flows and vents

• Dead legs / ends present

• Infrequently used outlets not flushed weekly

• No cleaning of shower heads

• Evidence that some Water treatment company reports do not reflect the inadequate management, treatment and control of legionella at the homes

When is legionella sampling required?

• Where storage and distribution temperatures are

reduced from those required

• Where an outbreak is suspected or identified

• Where assessment identifies it is necessary to

help monitor effectiveness of controls

Where to sample?

• cold water samples -taken from the cold water tank/s and

furthest outlets

• hot water samples

- the nearest tap to the hot water tank outlet plus the return

to the hot water tank (if re-circulating)

- base of hot water tank and furthest outlet from the tank

When is disinfection needed?

• If required temperatures not being achieved

• System has been substantially altered; or

• During or following an outbreak

Other issues to consider

What is an infrequently used outlet?

What is the impact of green technologies or energy conservation on Legionella control?

How many people are contracting Legionnaires disease from care homes?

RIDDOR does not require non-worker reports of disease to HSE –but requirement to report to HPA

Frequency of Monitoring

Temperatures

Monthly Measure the temperature at the hot and

cold water sentinel outlets and the hot

water tank

Six monthly

Check the temperature at the cold water

storage tank/s (at least once in winter

and once in summer during a hot

period);

Annually Check a representative number of cold

water outlets on a rotational basis

Frequency of water temperature checks

The Frequency of Other Checks

At least weekly Flush infrequently used hot and cold

water outlets

At least 3 monthly Clean and de-scale or replace shower

heads and hoses

At least annually

Visually inspect the cold water storage

tank/s and clean and disinfect as

required

Check the schematic diagram/s of the

H &CW system to ensure they are correct

and up to date (eg addition or removal of

water tanks and outlets)

Note: All checks should be carried out using safe systems and some checks or corrective

actions may need to be done by an external competent person

Frequency of other checks

Further information

HSE H&SC Legionella webpage:

http://www.hse.gov.uk/healthservices/legionella.htm

HSE Legionella H&CWS webpage:

http://www.hse.gov.uk/legionnaires/hot-and-cold.htm

HSE SIM – Control of Legionella in H&CWS http://www.hse.gov.uk/foi/internalops/sims/pub_serv/07-12-07/index.htm

HSE ACOP L8: http://books.hse.gov.uk/hse/public/saleproduct.jsf?catalogueCode=9780717617722

HSE ACOP HSG274 Part 2

http://www.hse.gov.uk/pubns/priced/hsg274part2.pdf

HSE Safety Notice: http://www.hse.gov.uk/safetybulletins/legionella2.htm