by Bill Andresen, Sask Water, Outlook, SK
Before determining usefulness and required treatments for rural water supplies, a proper water analysis must be done. This can become confusing because there are many different tests which can be done by various labs and companies.
The analytical fees can be quite high so proper advice should be obtained from an appropriate government agency before submitting the sample. At this time, proper sampling procedures should also be discussed. For certain tests, proper sampling and preservation is important for accurate analysis of samples.
The water samples you take should be representative. Water samples from test holes will not be representative of water from a developed aquifer. Choose an outlet as close to the source as possible. For most domestic samples, allow water to run through the faucet for about five minutes (10 minutes if pump and well are offset a long distance) and then fill the sample container.
When water treatment is installed, you may want a "before" and "after" sample for chemical analysis. In this case, take the untreated sample at the source and the treated sample from the household. Be sure to mark the sample containers accordingly.
Some examples of tests are:
1. Drinking Safety Tests
2. Domestic Suitability Tests
3. Livestock Suitability
4. Spray Water Suitability
5. Irrigation Suitability
6. Special Tests
When the results of your tests are received, interpretation of the results will probably be required as the results will be numbers only.
An appropriate government agency can help you with the interpretation and make specific recommendations for treatment.
Coliform Bacteria
Coliform bacteria are commonly derived from faecal matter. They are found in the tract and in soil and sewage. The presence of a few coliform (values up to 5) may not count, but caution is advised (see Table 3). The "overgrowth" result indicates that many types of bacteria, some of which may be potentially dangerous, were present in the water sample. Their presence conceals the identification and interpretation of the coliform bacteria test. Review sampling procedures, ensure the water supply is adequately protected and resubmit another water sample.
| Total Coliform | Interpretation |
| Bacteria per 100 mis. | |
| 1-5 | Values up to 5 may not be significant. Caution, possible pollution. Take another sample. |
| 5-100 | Unsafe for drinking. Contamination is likely or consequent results from delay in receipt of sample. Common with new wells before disinfection and shallow dug wells which are not properly sealed. |
| 100 | Unsafe for drinking. This water is contaminated and should not be used for drinking under any circumstances. |
| Coliform unmeasurable because of other bacteria |
Unsafe for drinking. Harmful bacteria may be present. |
| Chemical | Range of Concentrations | |||
|---|---|---|---|---|
| Satisfactory | Poor | Not recommended | Unsuitable | |
| Total Dissolved Solids (mg/L) | up to 1500 | 1500-3000 | 3000-4000 | over 4000 |
| Hardness (mg/L as CaCO[3]) | up to 500 | 500-1000 | 1000-2000 | over 2000 |
| Alkalinity (mg/L as CaCO[3]) | up to 500 | 500-1000 | 1000-1500 | over 1500 |
| Chloride (mg/L) | up to 250 | 250-500 | 500-1000 | over 1000 |
| Sodium (mg/L) | up to 300 | 300-500 | 500-1000 | over 1000 |
| Sulphate (mg/L) | up to 400 | 400-800 | 800-1200 | over 1200 |
| Nitrate (mg/L) | (this is the same as 10 mg/L nitrate as nitrogen) | |||
| Iron (mg/L) | up to 0.30 | .3-1.0 | 1.0-7.0 | over 7.0 |
| Manganese (mg/L) | up to 0.05 | 0.05-0.20 | .2-0.5 | over 0.5 |
| pH (hydrogen ion conc.) | 7.0-9.5 | 6-7, 9.5-10 | 5.5-6, 10-10.5 | <5.5, >10.5 |
| Total Dissolved Solids mg/L | 100-1500 | 1500-3000 | 3000-5000 | |
| Hardness mg/L | 0-200 | 200-500 | 500 | |
| Calcium mg/L | 0-100 | 150 | ||
| Magnesium mg/L | 0-100 | |||
| Sodium mg/L | 0-300 | 300-500 | 500-1000 | |
| Alkalinity mg/L | 0-500 | 500-1000 | 1000 | |
| Sulfates mg/L | 0-500 | 500-1000 | 1000-2000 | |
| Nitrates | 0-90 | 100 | ||
| pH, units | 7-8.5 | 6.5-9.5 | 6.0, >9.5 | |
| Iron mg/L | 0-0.3 | 0.3-1.0 |