Fecal coliform bacteria are found in the feces of humans and other warm-blooded animals. These bacteria can enter rivers directly or from agricultural and storm runoff carrying wastes from birds and mammals, and from human sewage discharged into the water.

Fecal coliform by themselves are not dangerous (pathogenic) . Pathogenic organisms include bacteria, viruses, and parasites that cause diseases and illnesses. Fecal coliform bacteria naturally occur in the human digestive tract, and aid in the digestion of food. In infected individuals, pathogenic organisms are found along with fecal coliform bacteria.

If fecal coliform counts are high (over 200 colonies/100 ml of water sample) in the river, there is a greater chance that pathogenic organisms are also present. A person swimming in such waters has a greater chance of getting sick from swallowing disease-causing organisms, or from pathogens entering the body through cuts in the skin, the nose, mouth, or the ears. Diseases and illness such as typhoid fever, hepatitis, gastroenteritis, dysentery, and ear infections can be contracted in waters with high fecal coliform counts.

Pathogens are relatively scarce in water, making them difficult and time-consuming to monitor directly. Instead, fecal coliform levels are monitored, because of the correlation between fecal coliform counts and the probability of contracting a disease from the water.

Cities and suburbs sometimes contribute human wastes to local rivers through their sewer systems. A sewer system is a network of underground pipes that carry wastewater.

In a separate sewer system, sanitary wastes (from toilets, washers, and sinks) flow through sanitary sewers and are treated at the wastewater treatment plant. Storm sewers carry rain and snow melt from streets, and discharge untreated water directly into rivers. Heavy rains and melting snow wash bird and pet wastes from sidewalks and streets and may "flush out" fecal coliform from illegal sanitary sewer connections into the storm sewers.

In a combined sewer system, sanitary wastes and storm runoff are treated at a wastewater treatment plant. After a heavy rain, untreated or inadequately treated waste may be diverted into the river to avoid flooding the wastewater treatment plant. To avoid this problem, some cities have built retention basins to hold excess waste water and prevent untreated wastes from being discharged into rivers. Without retention basins, heavy rain conditions can result in high fecal coliform counts downstream from sewage discharge points. That is why it is important to note weather conditions on the days before a fecal coliform measurement.

Fecal and total coliform standards for water used for drinking, recreation, and treated sewage

Sampling Procedures

  1. Remove the stopper or cap just before sampling and avoid touching the inside of the cap.
  2. If sampling by hand, use gloves and hold the bottle near its base. Plunge it (opening downward) below the water surface, then turn the bottle underwater into the current and away from you.
  3. Avoid sampling the water surface because the surface film often contains greater numbers of fecal coliform bacteria than is representative of the river.
  4. Also, avoid sampling the sediments for the same reason, unless this is intended. The same general sampling procedures apply when using the extended rod sampler.
  5. When collecting samples, leave some space in the sample container (an inch or so) to allow mixing of the sample before-pipetting.

It is a good idea to collect several samples from any single location on the river to minimize the variability that comes with sampling for bacteria. If possible, sterilization should occur between sampling sites. Ideally, all samples should be tested within one hour of collection. If this is not possible, the sample bottles should be placed in ice and tested within six hour

Testing Procedure (the Quick and Easy way)

Detection of Water Born Coliform and Fecal Coliforms with Coliscan Easy Gel

This new process for coliform and fecal coliform testing does not require an incubator or water bath.

  1. Use a sterile calibrated dropper to collect a 1 ml water sample and deposit the sample into bottle containing liquid coliscan medium (this procedure may be done in the field and the coliscan-water mix can be kept on ice until returning to the lab).
  2. Pour the coliscan water mix into a pre-treated petri dish and swirl to cover entire bottom of petri dish.
  3. Place the petri dish containing the coliscan-water mix in a warm place and incubate for 24-48 hours (this is best done in a place such as an incubator which holds the temperature in a range of 850-950' F).
  4. Count the red colonies in the petri dish as coliforms and the purple colonies as fecal coliforms (E. coli). (White or blue-green colonies should be noted, but they are not classified as coliforms or fecal coliforms).

Gels can be attained through:

Traditional Fecal Coliform Testing Procedure

  1. First, sanitize the forceps by dipping forceps in alcohol, then burning alcohol off with a flame (an alcohol lamp works well). Do not place the hot forceps back into the alcohol.
  2. Using the sanitized forceps, place an absorbent pad in the sterile petri dish. Be careful not to touch the pad with your fingers.
  3. Unscrew the neck of the broth plastic tube (ampoule) or use an ampoule breaker if needed, and drain the broth onto the pad (The broth is liquid food for fecal coliform bacteria). Put the top on the petri dish and set aside.


Fecal Coliform Test Equipment Items

  1. Sanitize forceps with alcohol and flame again,
  2. Unscrew the top half of the filtration system and place a sterile filter paper on top of the filtration system's membrane with forceps; grid side up. Be sure the filter lies completely flat with no wrinkles.
  3. Screw on the top half of the filtration system to the bottom half.
  4. Before taking a sample, use a pipette to rinse the filtration system with a small amount of distilled water. Add the water through the hole in the top of the system. (There should be two or three rubber stoppers on top of the filtration system, and one hole without a stopper. See Figure 3.8).
  5. Determine the desired volume of water (in ml) to be tested based upon the water source (See chart below for suggested sample volume sizes). Place the pointed end of the pipette into the water to be sampled and lower into the water until the desired sample size, as shown by volume markings on the side of pipette, has been drawn into the pipette. A rubber bulb attached to the top of the pipette may be required to obtain the desired volume. When there are high numbers of fecal coliform, a proper sample should not exceed 60 colonies on the petri plate. The higher range affects the colony sheen or color development resulting in errors in making a proper count.

Adapted from Standard Methods for the Examination of Water and Wastewater.

  1. Place the end of the pipette into the open hole on top of the filtration system, and release the water sample into the funnel.
  2. With the filtration system level, use the suction pump and draw all of the sample and distilled water through the filter while swirling so that the number of bacteria adhering to the upper filtration system is reduced. (Warning: be careful when pushing the plunger back into the syringe; you want to avoid pushing air back into the filtration unit and forcing the filter off the membrane.) Draw the water through the filter until it appears dry.
  3. Unscrew the top half of the funnel, and carefully remove the filter with the sanitized forceps.

If you do not have a water bath, one might be available at a local university, community sewage treatment plant, or local laboratory. If no water bath is available in your community you might try a hot air incubator if it holds temperature. Recognizing that a water bath is relatively expensive, multiple schools within a watershed involved in a water monitoring program might want to purchase one water bath for the entire program.

  1. Open the top of the petri dish, and slide the filter across and into the dish, with the grid side up. Petri dishes should be incubated within 30 minutes of filtering the sample; this will ensure heat shock of any non-fecal coliform organisms. Be sure to record the date, site, and volume of sample on the frosted part of the petri dish.
  2. Enclose the petri dish in a waterproof bag (to avoid leakage) and then put into the water bath. Dishes may also be sealed with waterproof tape (freezer tape) to avoid leakage. Incubate for 24 hours (+/- 2 hours) at 44.5'C. (Temperature must be maintained within a range of ±0.25'C to 44.5'C.) Petri dishes should be inverted during incubation to avoid condensation. Please wash your hands after this test.
  3. After incubation, carefully count the bacterial colonies on the filter, using a magnifying glass (10 x) or unaided eye. You might want several people to verify the bacterial count. Each bluish spot is counted as one fecal coliform colony. Cream or gray-colored colonies are nonfecal coliform. Fecal coliform colonies should be examined within 20 minutes to avoid color changes that occur with time. Some common fecal coliform culture problems can be seen below.
  4. It is important to report the highest fecal coliform value rather than an average value.


When the experiment is done correctly there should be
20-60Coliform colonies evenly dispersed


Growth around sealing edge means
unclean filter holder or poor seal


A dry spot without growth shows improper seating
of filter


Sample size too large


Uneven distribution os from not swirling the
sample while filtering or not adding distilled
water to sample

A word about sterilization ...

It is essential to sterilize sample bottles, pipettes, and filtration system before sampling. Sterilization can be accomplished by using an autoclave; 121' C for 15 minutes. If an autoclave is not available, the home economics department may have a pressure cooker that they might be willing to lend to the water quality monitoring program. If a pressure cooker is used, please be sure that it has a working pressure gauge. The gauge may be checked with the county cooperative extension service. The pressure cooker should be ran at 15 psi. to properly sterilize sample bottles, pipettes and filtration system.

If these two pieces of equipment are unavailable, an oven can be used. The oven must attain a temperature of 170' (±10 ‘C) for not less than 60 minutes. The plastic filtration system cannot, however, be placed in a dry oven because the system will melt. The same holds true for plastic sampling bottles. The filtration system can, however, be placed in boiling water for 5 minutes to sanitize it. Petri(I dishes, culture media, absorbent pads, and filters are sterilized and packaged. Equipment that has been inadequately sterilized may interfere with fecal coliform growth.

... and sampling design

If the purpose of sampling is to determine fecal coliform levels at a river reach, then samples should be taken beneath the water surface and in the current (if there is one). If the purpose of sampling is to confirm suspected sources of fecal coliform contamination, then samples should be taken just downriver from the source (like the mouth of a storm drain), and other samples should be taken upriver from the source for comparison.

There is also wet-weather sampling and dry-weather sampling. Wet-weather sampling involves sampling during and just after a rainstorm, often at timed intervals. It is done if fecal coliform contamination is suspected from storm drains carrying urban storm water runoff. Wet-weather samples can then be compared to samples taken during a period of dry weather (dry-weather samples). The bottles used for the dissolved oxygen test might also be used for the fecal coliform test.

Try to avoid sampling stagnant areas of rivers. The extended rod sampler is an effective device for obtaining a sample in the current. If sampling rivers in which little current exists, push the sample bottle underwater away from your body, thereby creating a current.