Water Quality

Interpretation of results – Umgeni Water

>4000 – some non-natural faecal contamination is likely.
>7000 – a much higher likelihood of faecal contamination.
>10000 – sewage pollution is almost certain, with concomitant serious water quality and environmental risk.
>100 000 – sewage pollution is very bad, with related very high risk.
>241000 – sewage pollution is extreme, with extremely high likelihood of major environmental damage and severe health risk.

Interpretation of results – DUCT

DUCT’s River Water Quality Assessment Guidelines updated 27 October 2013
E. coli bacteria occur naturally within mammal digestive systems and most of them are not harmful in any way. However, because they are so common E. coli data are considered useful as a general indicator of a wide range of other potential human pathogens, and thus also of the possible presence of sewage related water quality problems. In the absence of other data, E. coli numbers are useful in allowing a general assessment of other potential water quality risks.

E. coli count/100mL	Water quality “assessment”		Assessment of probable risk to canoeists
*0 – 130		Excellent – Considered acceptable for full contact recreation – excellent / likely natural catchment.	Extremely low risk.
130 – 1000		Good – within the range expected for quite good catchment conditions, but significant / increasing risk of illness if used for full contact recreation (e.g. swimming).	Very low risk.
1001 – 4000		Fair resource condition, natural sources (i.e. not sewage related) are still possibly the E. coli source, but increasing likelihood of human faecal / sewage contamination at the upper end of this range. Unacceptable for swimming.	Low, but increasing risk.
4 001 – 10 000		Degraded – Significant faecal input or some sewage contamination is indicated. Other water quality parameters are likely to be poor.	Moderate risk (approx. 1 in 10 may get sick).
10 001 – 25 000		Unacceptably Poor, sewage contamination definitely present.	Moderately high canoeing risk (approx. 1 in 5 may get sick) – some likelihood of illness esp. in white water.
25 001 – 50 000		Bad, with significant sewage contamination and negative environmental consequences.	High risk (approx. 1 in 3 may get sick) – consider not canoeing or paddle on flat water only, with no risk of falling out.
>50 000		Severely contaminated with significant sewage contamination and negative environmental consequences.	Very High canoeing risk – (approx. 1 in 2 paddlers may get sick). Avoid canoeing!

*Note, the only acceptable value for drinking water quality is ZERO E.coli counts per 100 mℓ. No naturally occurring surface water should be expected to have E. coli this low (even in large dams). If zero E. coli results are achieved for a natural water, contamination by disinfectants is the likely cause and this may be masking other significant potential pollutants.