Scientific Services - Microbiological Examination of Drinking Water

Microbiological examination of drinking waters

It is very important to ensure that drinking water is not contaminated with micro-organisms. We determine whether there is possible contamination of water with agents that might cause illness or disease by checking whether there are increased levels of faecal coliforms.

We measure the total colony count and levels of total and faecal coliforms present in water for comparison against the appropriate Regulations.

A summary of the recommended levels can be downloaded as a pdf (46 Kb).

Please ask us if you would like further explanation of your test results.

Regulations

Various Regulations control the microbiological safety of water for human consumption ie, The Natural Mineral Water, Springwater and Bottled Drinking Water Regulations 1999, The Water Supply (Water Quality) Regulations 2000 and The Private Water Supplies Regulations 1991.

Here are the Microbiological Guidelines and Standards for Drinking Water

Type of Water	Parameters	Permitted Concentration or Value	Guide Level
Private Supplies
Classes A to E and 1 to 4	coliforms/E. coli colony counts at 22ºC and 37ºC	0/100 mL	No significant increase over normal levels. See note (a) No organism detrimental to public health
Class F	coliforms/E. coli	0/100 mL	No significant increase over normal levels. See note (a) No organism detrimental to public health
Natural Mineral Waters
sampled any time up to sale	coliforms/E. coli enterococci Pseudomonas aeruginosa sulphite reducing clostridia parasites/pathogens	0/250 mL 0/250 mL 0/250 mL 0/50 mL Absent
within 12 h of bottling	As above plus colony count at 22ºC/72 h colony count at 37ºC/48 h	. 100/mL 20/mL
Drinking Water in Containers
at any time	coliforms/E. coli enterococci Pseudomonas aeruginosa sulphite reducing clostridia colony counts at 22ºC and 37ºC	0/100 mL 0/100 mL 0/100 mL 0/20 mL Should show no appreciable increase after bottling
within 12 h of bottling	As above plus colony count at 22ºC/72 h colony count at 37ºC/48 h	. 100/mL 20/mL	. 20/mL 5/mL
Vending Machines	coliforms/E. coli	<10/mL

(a) For colony counts on drinking waters some of our customers use guideline levels of <10 colonies/mL at 37ºC and <100 colonies/mL at 22ºC.

Additional Tests

The Leicestershire Scientific Services also provides a comprehensive chemical testing service on waters. Please contact us for more details.

scientificservices@leics.gov.uk 0116 305 5640

Microbiological examination of drinking waters

Regulations

Type of Water

Parameters

Permitted Concentration or Value

Guide Level

Additional Tests

further information