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Kapiti Water
Quality Reliable Sustainable
24 Hour Emergency Number: 0800 486 486
General Enquiries: (04) 296-4700 |
Raumati, Paraparaumu and Waikanae Water Supply
The Waikanae water treatment plant was established in 1977 to supply water to Waikanae, Paraparaumu and Raumati. The plant primarily sources its water from the Waikanae river, but when the river levels are low supplementary water is provided from groundwater bores. This ensures the ecosystem of the river is protected. The plant processes the raw water from both the river and the bores to provide clean, safe water for distribution to the homes, farms, and businesses of the area.
The Waikanae borefield has improved the water supply level of service for the Central area. With responsible water use, the Council is able to provide a "Hand Held Hose Anytime" level of service during the dry summer period. This allows people to wash down their house, boat or car, as well as provide water for sensible irrigation.
Click here for good garden practice for using water outdoors. If you have a leaking tap or want advice on rainwater, greywater or bore use, the Green Plumber can visit your home.
Current Water Use Level for Waikanae
Evenign sprinkler use.
Shut downs in Waikanae
None at present
The Water Treatment Process
1. Raw Water
The quality of the raw water from the bores is different to that from the river so the two sources require different pre-treatments. The bore water contains large amounts of dissolved minerals from the soil including iron and manganese. These metals are removed by potassium permanganate.
The river water has a low pH which can lead to corrosion of the metal pipes and fittings in the plant and reduces the efficiency of the chemicals used to treat the water. As a result, lime is added to condition the pH to avoid these problems.
2. Coagulation and Flocculation (removing solids)
The water from the two sources contains a range of suspended solids which give the water a dirty look and taste. These solids normally have a negative charge that causes them to repel each other. To neutralise this charge a chemical, Aluminium sulphate(Alum) or poly aluminum chloride (PACI), is added to the water in a rapid mixer. This allows the solids to clump together, in a process called coagulation.
The next step is to add a flocculent. This flocculent is a polymer which binds to a number of clumps produced during coagulation. The large dense particles settle out of the water.
3. Powdered Activated Carbon (PAC) (removing the taste)
During the summer, algal blooms grow in the Waikanae River. In the last few summers algae that produce toxins which cause serious health problems have been found in the river. To extract these toxins, and the tastes and odours created by the algae, a new system has been built to add PAC to the water. The PAC particles have a very large surface area on which the toxins are absorbed. The PAC and attached toxins are then able to be removed from the water in the next stage of treatment.
4. Clarification (removing remaining solids)
Following the addition of the chemicals, the water enters a clarification tank which allows the particulates in the water to settle to the bottom. In this step, suspended solids are removed from the water. The solids that settle to the bottom are withdrawn, processed further to reduce the water content and are pumped to the wastewater treatment plant. The clear water from the top of the clarifier is pumped to the filters.
5. Filtration (removing the solids and bacteria)
Waikanae water treatment plant uses rapid sand filters with a dual media comprised of anthracite and sand. The water passes through the medium and any remaining suspended solids are contained by the filter. When the filter becomes clogged, water and air run backwards through the filter to dislodge the particles blocking it. This "backwash water" is sent to the sewer.
6. Disinfection and Distribution (keeping the water clean)
Chlorine gas is added to the water. This disinfects the water and provides protection against microbial growth in the pipes and reservoirs. Fluoride is also added before distribution to promote dental health. The water is stored in the clear water tank before entering the distribution system.
Water Quality
The water is constantly monitored to ensure it meets the compliance limits set out in the 2005 New Zealand Drinking Water Standards (NZDWS) at all times. To find out what's in your water click here for a copy of the 2005 Water Quality Report.
Grading
The Ministry of Health publishes a yearly grade for each public water supply in New Zealand. The grade reflects how well the plant complies with the NZDWS and consists of two parts.
The first part gives an indication of how well the water source and treatment process comply by assigning a grade between A1 and E. The second part evaluates the distribution system, which delivers the water from treatment plant to homes and businesses, and assigns a grade between A and E.
Our current gradings (1995) are:
The Waikanae water treatment plant and source: A
Distribution System: A
Note: All water treatment plants in the district are currently under assessment by drinking water assessors of the Ministry of Health as defined under the NZ drinking water standards 2005 which became effective on January 2006.
Taste
Changes in the taste of the water are often caused by issues in the household. If you are concerned about the taste of your water, click here to find out about some of the common causes for changes in the taste of your water before contacting the council.
Water use and conservation
Check out the Green Gardener and Green Plumber pages for ideas on how you can create the lifestlye you want with the water available.
