Microsoft Word - HOW TO WATER SAMPLE revised.doc

Midwest Assistance Program How to Take a Routine Bact-T Sample 1

How to Take a Routine

Bac-T Sample

Midwest Assistance Program How to Take a Routine Bact-T Sample 2

Why Take a Water Sample?

A water system operator’s first priority is to provide safe drinking water to the public that

system is serving. The easiest way to insure that the water is safe for consumption is

through bacteriological testing. A good bacteriological testing program will accomplish

three things:

1) Prevent the spread of water borne diseases.

2) Limits the liability exposure for the water system

3) Helps identify system problems

Water testing may appear to be rather unimportant and boring. This is far from the truth,

water testing is extremely important. If sampling is done correctly, it will prevent illness

or even death. IT’S ALSO THE LAW.

The Montana Department of Environmental Quality (MDEQ) and the Environmental

Protection Agency (EPA) require that all public water supply systems sample the water

that is provided to the public on a regular basis.

When to Sample

As mentioned above, MDEQ and EPA require that all public water supply systems

sample their water on a regular basis- for bacteriological growth. The number of

samples that are required each month is determined of the population served.

Regardless of the size of the system, there are certain general principles that should be

applied.

1) It is best to take the samples at the same time each month.

2) Select a time that is early in the month. (First two weeks)

Select a sampling day early in the week. (Monday, Tuesday, and

Wednesday)

Why take the sample the same time each month? This will assist in long-term

planning and insure that enough time is allotted to perform the sampling properly. It will

also help other operators keep your sampling schedule up-to-date in case you are not

available to take the sample.

Why select a time that is early in the month? This will ensure the operator enough

time to resample if a sampling error occurred or a bad sample was detected. The operator

would have time to be notified by the laboratory and ship a new sample or samples for

testing. Sampling is recommended within the first two weeks of a month.

Why select a day early in the week? This will insure that the sample, when shipped,

will arrive at the laboratory during the mid part of the week. If a sample were shipped

later in the week it may arrive during the weekend when there may not be anyone to

Midwest Assistance Program How to Take a Routine Bact-T Sample 3

begin the analysis. Samples must begin the analysis process within 30 hours of being

collected. Samples over 30 hours old cannot be used for compliance purposes.

Shipping the Sample to the Laboratory

Talk with your local postmaster when determining the best way to send the sample to the

laboratory. In some small communities the public mail service may not be fast enough.

Ensure that the sample will reach the laboratory within 30 hours from time of collection.

It is also important to know when the mail leaves the post office. An operator may not

want to collect the sample at 8:00 in the morning if the mail does not leave the post office

until 4:30 in the afternoon. Private shipping services may be an effective alternative.

It may be best for the system operator to personally deliver the samples to the laboratory

or to the nearest shipping service that will ensure 30-hour delivery to the laboratory.

Where to Sample

The Coliform Rule requires that each water supply system develop and follow a written

sampling site plan. Each plan must specifically identify sampling points throughout the

distribution system. Sampling plans must be approved by the regulatory agency and it

will be necessary to check with your regulatory agency to determine if any additional

information is needed before submitting the plan.

The owner or operator of the water system prepares the sample site plan. The plans are

simple maps that show in detail the water source, treatment, storage, distribution system

and pressure zones. The site plans are used to identify where the routine and repeat

samples will be collected. Specified numbers are assigned to each site and used on the

monitoring report forms sent in with water samples.

Most sampling sites are rotated across every three months. This ensures that the entire

distribution system is being monitored on a rotating basis. Each sampling site should be

marked on the map. The address and which months’ sampling occurs should be labeled

on the map. If repeat samples are necessary, the sample sites should also be marked on

the map and labeled repeat sample locations. Also on the map the system should have

three alternative sampling sites, in case of emergencies.

Example 1:

If a water system were required to submit one (1) bacteriological sample per

month, the sample site plan would have a total of three (3) routine sampling

sites indicated by a number and repeat sample sites for all three sampling

sites. There would also be three (3) alternative sampling sites labeled on the

site plan.

Midwest Assistance Program How to Take a Routine Bact-T Sample 4

Example 2:

If a water system is required to submit three bacteriological samples a

month, the site plan would have a total of nine routine sampling sites

indicated by a number and repeat sample sites for all nine sampling sites.

There would also be three alternate sampling sites labeled on the site plan

Sampling site plans are extremely helpful when discussing monitoring results with the

regulatory agency, identifying monitoring problem areas, and conducting sanitary

surveys and other inspections.

The Sampling Site

Distribution System-Wide Selection

Sampling locations should be chosen to systematically cover the entire distribution

system. Trouble spots, such as dead ends or low flow areas, SHOULD NOT be avoided.

This can reveal localized contamination.

Outdoor Faucets

Outdoor faucets should not be used because of the possibility of contamination on the

surface and interior of the faucets. Frost-freeze hydrants should not be used either. The

chance of contamination is greatly increased by the elements of Mother Nature, animals,

children and dust coming into contact with the faucets.

If a sample must be taken from an outdoor faucet, use extreme caution. Avoid dust,

splashing, rain, snow and other sources of contamination. The faucet should be

disinfected and flushed for a period of time to ensure disinfectant has been removed.

Indoor Faucets

Indoor faucets in a clean area are the best sites

for sampling. Make sure the faucet is not

connected to a water softener, in-line filtration

units, or hot water heater. These types of

connections would not supply the water that is

representative of the water in the distributions

system. Avoid sampling from faucets that

have swiveling heads, faucets with the hot and

cold water under the same valve, or faucets

with leaking valves.

Systems should be disinfected after repairs or new plumbing has been installed prior to

collecting bacterial samples. Samples may not be collected from a disinfected system

until 72 hours have elapsed since the disinfectant was flushed from the system.

Sampling

Faucet

Midwest Assistance Program How to Take a Routine Bact-T Sample 5

Some circumstances may require that the water system install a separate faucet that

would be used only for water sampling needs.

Other Types of Faucets

Mixing Faucets (faucets where hot and cold water

come through same tap) should not be used

because water passing through the “hot” waterside

may not be representative of the water in the

distribution system. Water in the hot water tank is

more likely to grow bacteria because the warm

water may promote growth.

Threaded taps should be avoided as a sampling

site. Bacteria can grow in the grooves of the

threads. NEVER take a sample from taps that are clearly contaminated (scum or build-up

around tap and base of faucet).

Avoid collecting samples from the following faucets:

1) Faucets supplying dishwater in cafes, coffee

shops and other eating establishments are

higher-than-usual possibilities for bacterial

growth.

2) Swing spouts - bacteria can grow where the

faucet pivots.

3) Faucets positioned close to the bottom of the

sink or the ground.

4) Leaky faucets or faucets that allow water to

seep around the valve stem.

These types of faucets can introduce contamination into the sample.

It is becoming extremely difficult to locate faucets that are not of the types mentioned

above. A representative sample may be taken from some of the types mentioned above,

if a good sampling technique is used. Remember that if one is used, your chances of

contamination are greatly increased.

Midwest Assistance Program How to Take a Routine Bact-T Sample 6

The Sample Container

Most laboratories supply sterilized and chemically pretreated containers to be used in

taking a water sample, along with an approved mailing carton, forms and a cold pack to

keep samples cool.

The container should have a wide mouth and capacity of at least 125-ml. Use only

containers that have been supplied or approved by the laboratory that will be conducting

the water testing.

The caps used on a sample container must be sterilized just as the containers are. Always

examine sample containers when they are received from the laboratory. If any of the

caps are loose, off or cracked discard damaged containers and call the laboratory for

additional sample containers.

Use only sample containers that were recently sent to the water system. Containers that

have been stored for a period of time could have increased chances of being

contaminated.

Be sure that all sample containers have labels. Each container should have a label to

write the date, time, location, samplers’ name, water systems name and PWSID. Also

ensure that the necessary forms are sent from the laboratory to ensure proper analysis of

the sample.

Disinfecting the Sampling Site

Sometimes it is necessary to disinfect the sample site before the sample is taken. The

preferred disinfection techniques is wiping the surface of the fixture with bleach or

spraying bleach onto and into the faucet opening. Allow bleach to air dry before

flushing the faucet. Remember when using bleach, ensure that the fixture has adequate

time to flush. Any residual from the bleach will give an invalid sample result.

Heat is another recommended disinfecting process. The sampling fixture can be heated

with a torch to disinfect it. This technique may remove any local contamination so that

the operator may get a representative sample of the water in the distribution. If heating or

flaming the fixture is done, remember that this may create a fire hazard. Also, the heat

from this process could melt any plastic fixtures, mar the finish of the fixture, or damage

the valves and seats. If this happens the utility department may be liable for damages.

Midwest Assistance Program How to Take a Routine Bact-T Sample 7

Water Sampling Procedure

Step 1

Remove any attachments on the faucet. Look for aeration devices, hoses, water

purification devices and screens.

Step 2

Turn on the water and allow it to run in a steady

stream for 5 to 6 minutes. This will ensure that

the line is flushed sufficiently to get a

representative sample of the water from the

distribution system. Additional time might be

needed if the water tap is located a long distant

from the main distribution line.

ALWAYS SAMPLE THE COLD WATER, NEVER

SAMPLE HOT WATER

Step 3

(USE EXTREME CAUTION)

After the lines have been flushed, open the container. (The

use of latex gloves will reduce the chance of contamination from the

sampler.)

Do not set the container cap down! Hold it with fingers

away from the edge and away from splashing water.

DO NOT hold the lid upside down.

Do not rinse the container, and do not allow the

container to overfill. This may wash out any de-

chlorinating agent provided by the lab. If this happens,

discard the container and take a new sample using a

fresh container.

Midwest Assistance Program How to Take a Routine Bact-T Sample 8

Step 4

Grasp the container near the bottom (see picture

above). NEVER touch the inside of the cap and the

container.

Quickly position the container under the flowing

stream of water. Ensure that the water stream is

maintaining a constant stream. Also, be sure water

from the outside of the faucet is not dripping into the

bottle during collection. DO NOT allow the container

or cap to touch the faucet or tap.

Step 5

Fill the container to the neck or indicated fill line. This will ensure that the proper

amount of water has been collected. 100 ml is the minimum the laboratory must have to

conduct a test. DO NOT over fill the container. Never allow container to overflow!

Step 6

Affix the cap on the container as soon as it is filled

and removed from the flow. Check to make sure that

your container is properly sealed, as the sample will

leak if not properly sealed.

Step 7

Turn off water and re-attach any fixtures or attachments that were removed.

Step 8

Using a waterproof ink pen, label the sample container.

The label should have the date and time when sample was

taken, location of sample site and sampler’s name and

PWS number. Some samples also need to have the

chlorine residual and any preservatives that were added to

sample.

Midwest Assistance Program How to Take a Routine Bact-T Sample 9

Complete the required sampling forms and chain of custody forms that the laboratory

sent with the sample containers. These sampling forms require a public water supply

identification number, the time and date the sample was taken, the location, sample

container size, the samplers name, address and telephone number. Plus the results of any

field-testing completed on the sample, such as pH, chlorine residual and temperature.

The sampling forms must indicate what type of testing (monthly Bac-T, VOC’s, Lead

and Copper.) is need for each sample container. Take note of anything unusual about the

sample (strong odors or color) and write it down on the form, also.

Step 9

Place the filled container, cold pack and completed

forms into the shipping container that the laboratory

sent.

Make sure your address and the laboratory’s address

is correctly labeled on the shipping container.

Remember that samples must begin the analysis process, at the laboratory, within 30 hours

from the sampling collection time.

Step 10

CLEAN THE SAMPLING SITE!

It’s important to leave the sampling site clean for reducing contamination of future

samples and maintaining good public relations with your customers.

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