The Loam Ranger – Testing water from rainwater tanks
Dear Loam Ranger,
Here is a sample of water from my rainwater tank. Is it safe to drink?
Why test?
Following the drought years of the noughts and the government rebates aimed at promoting the installation of home rainwater tanks, many old homes and all new homes in NSW are now self-sufficient in water for the garden and even for flushing the toilet and washing clothes. Of course, residents in the bush have always relied on rainwater tanks for everything, including drinking. These days we receive several requests a week to test tank water from all parts of NSW for its suitability for drinking or other uses.
Many factors determine the suitability of tank water for drinking, including:
- roof material (e.g. tiles encourage algae; corrugated iron releases zinc)
- local wildlife (think of bird and possum droppings: bacteria)
- local industry (e.g. mining, smelting, incineration: dust and heavy metals)
- local traffic (e.g. major highway versus rural road: dust and soot)
- tank material (concrete, steel or plastic: what dissolves out of them?)
- filters (fine, coarse or none?)
- first-flush devices (to flush out dust and droppings)
- screens (to keep out mosquitoes, frogs and anything that might drown).
Given all these factors, everything you can do to keep nasties out of the tank in the first place will increase the suitability of your water for drinking. So consider installing leaf guards, screens and first-flush devices. Even so, the only way to know for sure what’s in the water is to have it tested.
SESL tests
SESL offers a 24-hour turnaround for bacterial presence/absence and a 7-working-day turnaround for a full suite of tests (or 24-hour turnaround for a premium price if it’s urgent):
- Bacterial presence/absence: In 24 hours we can tell you whether any E. coli (short for Escherichia coli) or coliform bacteria are present. These are strong indicators of faecal contamination (“coli” = “of the colon”).
- Heavy metals (including zinc, iron, lead, cadmium, mercury and chromium).
- Nutrients (nitrate, nitrite, ammonium, sodium, chloride, fluoride, sulphate), which promote the growth of microorganisms in the water and can be harmful to humans in excess concentrations.
- Total plate count: We count how many bacteria grow on nutrient agar. From this number we can work back to the average number of all bacteria per litre of water. This test gives the number of bacteria in the water (including naturally occurring ones) but does not identify the specific bacteria present.
- Pesticides and hydrocarbons if requested.
All tests are conducted according to the Australian Drinking Water Guidelines.
What to send us
We need approximately 700 mL (for basic drinking water analysis) from each tank, taken at the outlet tap, in spotlessly clean containers.
Please call for pricing for 24-hour coliform testing, 7-day full testing and urgent (premium) testing.