Clean water is something we take very much for granted in
our modern daily lives, but if you give
it some thought, a lot of effort goes in to supplying water in volume, that is fit to
You only have to take the recent mayhem caused when
Cryptosporidium was discovered in the north west’s United Utilities water
supply which required people to boil their drinking water.
Water is complicated stuff, it does after all support life.
Fish absorb oxygen from their surroundings. Work your way down the microscopic
scale and you’ll find a whole spectrum of odd and unusual creatures that live
out their lives in water.
Some are harmful to us if consumed, which is why our
drinking water is treated to make it fit for purpose. That fitness for purpose
is of course only up to the point of delivery, usually your tap.
If not stored correctly, water can easily spoil just like
milk or perishable food.
In large quantities, it is not always practical to keep
water refrigerated (one method to stall the development of harmful bacteria).
Water bowsers offer the next best storage alternative,
especially if they are approved drinking water vessels and employ WRAS fittings
are pre-treated prior to filling and securely closed to preserve the integrity
of the water inside.
Providing these conditions are followed you can store
drinking water safely for 48 hours and then you need test it for its fitness
for purpose (drinking).
Since we launched our H2O on site water services earlier in
the year, we’ve become pretty busy testing and reporting on water quality.
As well as bowsers, drinking water is often stored in larger
vessels such as tankers or even pillow tanks.
Our standard test encompasses the following: Bacteria,
Nitrate, Nitrite, Hydrogen sulphide, Sulphate, Total hardness, total
alkalinity, total chlorine, free chlorine, Chloride, copper, Iron, Exact ph level, exact temperature, Coliforms
and E coli. Quite a list isn’t it ?
We also check fixtures and fittings for damage or potential
contamination. Inlets and outlets of vessels containing water to be tested are
sanitised prior to the test being taken to reduce to “negligible” the risk of
Testing is specifically colour based, with the colour of the
sample compared to calibrated test sheets, calibrated we hear you ask?
Imagine you have a sheet of card which has colours of test
variants printed on it. You’ve been using it a long time. You’ve left it out in
the sun a few times. The sunlight has bleached the page slightly.
The colours of your test sheet are no longer a fair
So, rather like everything else in the clever world of
quality control, comparison sheets are in turn compared against a master sheet
(calibrated to national standards) and certified as a true match to a specific
colour result. The sheet is known as a “correct colour chart”.
Coliforms and E coli tests are a little more involved. A
strict sampling procedure is followed to prevent accidental contamination.
Samples are incubated at a constant (calibrated) 35 degrees for 24 hours before
the test is conducted.
If the sample (which was yellow) is green or blue, those
yukky little Coliforms are present.
Testing for E coli involves viewing the sample under UV
light (again a measured wavelength of approximately 365 mm ) Zero fluorescence
means no E Coli, blue fluorescence indicates the little varmints be there.
Water containing E coli must be chlorinated using a set
procedure and measure of chlorine, then neutralised to make the water safe for
emptying into a public drain.
That’s environmental care. Putting harmless but non potable
water back into a biological environment where it will eventually be treated at
the water works, once again to be safely delivered fit for drinking to taps and
contained the contaminated water, must be treated and flushed to ensure the
contamination is neutralised before being used for drinking water purposes