Waterwatch: what parameters they
test and testing tips
The key water quality parameters monitored by Waterwatch
groups are:
Dissolved Oxygen
Biochemical Oxygen Demand
Temperature and Temperature Difference
pH
Turbidity
Total Dissolved Solids
Total Phosphates
Available Phosphates
Faecal Coliforms.
Lee Lau's Testing Tips
Disolved Oxygen
Fill the DO sampling tube (thin and long one) to the top with
sample water. Make sure no air bubbles in tube.
The reading appeared on the DC1600 only shows the transmittance
%. Please refer to Streamwatch Manual P.56 to convert the transmittance
% into mg/L.
To convert DO reading from mg/L to % saturation, please refer
to new Streamwatch Manual P. 51.
BOD (biochemical oxygen demand)
For BOD test, stand your air-sealed sample in dark. Test DO
on the 5th day, not 5 days later.
pH
Dip the test paper in sample water for 5 minutes.
Turbidity
Do not disturb the sediment when collecting sample water.
Just in case you have an old JTU tube, get a free NTU tube from
Lee. Please wash your tube regularly, especially the bottom
If water level stops between two marks, take the lower mark
(higher reading).
Faecal Coliform
To report faecal coliform counts, please only count the dark
blue and dark purple dots shortly after 24 hours
To report faecal coliform results in colony forming unit per
volume (cfu/100mL), please multiply the corresponding factor,
eg.,100X from a 1mL sample, 10X from a 10 ml sample and 1000X
from a 0.1 ml sample
Total P
If time is allowed, digest your total phosphates sample for
30 minutes.
Available P
If time is not allowed, skip the acid digestion section and
report the results as Available P.
Nitrate
Nitrates test is optional for blue kit users. Nitrates test
is not recommended using black kit.
TDS
Ask Lee to calibrate your TDS (for soluble salts or ions) meter
at least twice a year.
To clean probes, dip in alcohol for 15 minutes once a year.
