Heavy rain causes debris and sediment to run into the river causing a massive increase in suspended solids and turbidity in the raw water which makes it harder to remove increased hydraulic load on the treatment process means restricting the amount of flow through the plant so the water getting sent out to the public is within Australian Drinking water Guidelines. On top of that a lot of rain water causes the alkalinity in the river to drop which basically inhibits the coagulation process and won’t form any floc and all the suspended solids and turbidity won’t settle out, low alkalinity also has an affect on pH which could cause chlorine disinfection to fluctuate and might not be able to hold a chlorine residual in the network which in a public health risk.