UV
Ultra violet disinfection is the most common method of protecting against microbiological contamination. The UV is normally the last piece of equipment in a treatment system to ensure it has the fully treated water giving the highest level of light transmission possible. The correct sizing of the UV is vital to ensure the correct dose and contact time. A correctly sized UV is very effective at killing bacteria E.coli, Coliforms etc. and is safer than introducing chemicals which would also alter the waters taste. Discoloured water can lower the UVT (Ultra Violet transmittance) which reduces the effectiveness of the UV. A UV lamp must be changed as a minimum every 12 months and the UV quartz sleeve checked periodically to maintain light transmission.
PRE-FILTRATION
This usually consists of one or more cartridge type filters. There must be a cartridge before any UV to reduce particulates that bacteria could ‘hide’ behind. The size of filter is dependent on the water flow and quality of the water.
PH CORRECTION
Borehole and spring supplies often have water that is acidic with a pH of less than 7. A pH of less than 7 causes erosion of copper pipe, fittings & tanks/cylinders. The lower the pH the more aggressive this can be. This copper can leach into the water causing a blue/green staining and turning blonde hair green, but more importantly is then present in the water which you drink. A pH correction system elevates the pH to safer levels.
IRON AND MANGANESE REDUCTION
Borehole and some spring/surface supplies contain varying concentrations of minerals such as iron and manganese. This will cause brown and black staining and cause fouling of the pipe and taps in your house. These contaminants can be reduced by raising oxygen levels in the raw water to assist in ‘catching’ them on different medias. Another approach is ion exchange which regenerates on brine and in turn softens the water.
BOREHOLE AND BOOSTER PUMPS
The majority of borehole and booster pumps work alongside a pressure vessel and pressure switch. The pressure switch controls the pump with water demand (when low/high pressures are reached). The pressure vessel works as a water accumulator to reduce the amount of stop/starts of the pump, in turn reducing wear and extending the life of it. The correct size and air charge of the pressure vessel is vital. If your pump/pressure switch is short cycling the fault should be addressed as soon as possible. Pump controllers which are transducer controlled are also common place.
