City facing more water restrictions

Large swathes of Christchurch face another summer of water restrictions to keep levels of chlorine to a minimum while the council continues work to improve the safety of the drinking water supply.

Residents could be asked to cut their watering of gardens for up to two months – or endure more chlorinated water coming out of their taps.

Restrictions are likely to be imposed on about 60,000 homes in central areas, with the possibility of households being asked to water gardens every other day.

Limits are expected to come in for at least three weeks from January but could last up to two months under a worst-case scenario, council water boss Helen Beaumont said. ‘‘The reason for the water restrictions is that we need to continue working in the central zone. That area has always been the biggest problem for us – it is where we have the most work to do and where we have the least extra capacity . . . It’s always the garden watering that is a challenge for us because it’s such a big demand.’’

Councillors will consider the request to give council staff permission to bring in the restrictions tomorrow, while exact details of the prohibitions will come at a later date.

It comes after similar restrictions, the most drastic since the earthquakes, were ordered between March and May this year to help the council get a grip on water use while it repaired vulnerable wells.

The latest restrictions would cover the central zone, an area providing water for 42 per cent of the city stretching from Mairehau and Papanui in the north to the Port Hills, Hoon Hay and Linwood but that has the least excess capacity in its supply.

A new deep well will be drilled over summer to replace one at a pump station in Papanui that supplies about 3 per cent of the city’s water. That shallow well will need to be brought back into use while the new one is constructed to ensure residents have enough water, but because it has not been upgraded will have to be chlorinated, at 0.5mg/litre.

Without the water restrictions, council staff would have to bring more unsecure wells back online – meaning they would have to be treated – to make sure residents have sufficient water.

A reservoir at Cashmere is being emptied and repaired, also putting a strain on water supplies. Repairs to 106 council wells at 148 water supply bores have been completed as of the end of October, with sufficient progress to supply the whole of the city with water from secure wells.

About 30 per cent of Christchurch’s water is chlorine-free. The rest has low-level doses.