Drinking Water Testing PDF Print E-mail
Since 2005, RIDS-Nepal is providing drinking water supply to some of the villages in Humla. There are 2-5 public water taps in each village which are drained from the water sources (Stream/Drinking Water Spring Source) near from the village and each house is provided with the Slow Sand Water Filter (SSWF). Currently 15 villages of Humla are supplied with drinking water and water from the source (stream/DWSS), public water tap and Slow Sand Water Filter is tested for Ecoli.


E.coli is a type of fecal coli form bacteria commonly found in the intestines of animals and humans. E. coli is short for Escherichia coli. The presence of E. coli in water is a strong indication of recent sewage or animal waste contamination. For the detection the E. coli in the water, the following procedure steps are necessary:

  1. The Incubator (machine for incubation of E.coli) is taken.
  2. 100 ml of the sample water is taken in a beaker (Note: the time taken to gather the sample water from the source must not exceed 6hrs)
  3. The sterile sample cup and the forceps from the Incubator machine are taken and are sterilized by burning few drops of methanol inside the sterile sample cup.
  4. The sterile membrane is kept in between the filtration funnel and sterile sample cup.
  5. 100ml of sample water is poured in the filtration funnel.
  6. By using the hand vacuum pump, all the water at filtration funnel is drained down to the sterile sample cup such that all the E. coli bacteria are left behind on the sterile membrane.
  7. This sterile membrane is kept in the Petri-dish along with absorbent pad and the broth, a gel used for incubating the E. coli.
  8. This Petri-dish is kept in the heating machine of the Incubator machine for incubation period at 44oC for 16 to 18 hrs.
  9. After incubation period, the Petri-dish is taken out and the numbers of the yellow spots are counted.
  10. The E.coli number in 100ml is the corresponding numbers of spots in a filter membrane.

The standard drinkable water free from E.coli is 10 per 100ml for Humla.

RIDS-Nepal has had tremendous success in the Slow Sand Water Filter (SSWF) project. You can view the following graph to see what we mean. The following graph is generated by gathering the data from 3 independent sources 1. Gurgure Stream 2. Pico Stream (which powers RIDS-Nepal Pico-hydro) 3. Slow Sand Water Filter. It clearly demonstrate how effective the SSWF is and you can imagine how it has affected people's lives in Kholsi Village.



Turbidity is the cloudiness or haziness of water caused by individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality. For the measurement of the turbidity value, following procedure steps are necessary:

  1. An empty long tube with measuring scale of 5-2000 TU on surface of the tube and the black circular mark at the bottom, called turbidity tube is taken.
  2. Slowly the sample water is added in the tube with the continuous checking the visibility of the black mark from the top.
  3. The water is added till the black mark is visible.
  4. The turbidity value is the corresponding value shown by the measuring scale of the tube.

If the value is less than 1000, the water is said to be clear water. If greater than 1000, the water is said to be dirty.