KEY POINTS:
Te Kuiti residents boiling their water after an effluent leak may get have their supply flushed clean by heavy rain later this week, but there are fears a downpour could also cause another leak.
Residents have been boiling their drinking water since Saturday morning, after half a million litres of effluent leaked into the town's water supply overnight.
The untreated waste seeped out of a holding pond at a local meat works.
Environment Waikato resource use manager Chris McLay said it appeared the earth walls of the pond had cracked, spilling millions of litres of effluent into an underground hole.
This overflowed into a stormwater drain, which discharged about 500,000 litres into the Mangaokewa stream.
The stream feeds into the town's water treatment plant.
Environment Waikato scientists were monitoring the faecal contamination levels in the stream, which had been 100 times higher than normal eight hours after the spill, Mr McLay said.
Staff wouldn't know if the stream was clear of contamination for some days.
"(We) will also be closely monitoring the effects of heavy rain forecast this week," Mr McLay said.
"The rain could dilute the contamination, but could potentially cause further destabilisation of the ground."
Mr McLay said staff were investigating whether the meat works company was liable for the leak.
He said engineers with experience in land stability issues were working with the company to avoid any more earth movements at the site.
A public health warning remains in place, and Te Kuiti residents have been asked to reduce their household water use, boil drinking water for at least one minute, and have been warned not to swim downstream from the spill.
Children at local schools have been told not to drink from water fountains, and bottled water is being supplied by the Waitomo District Council.
Te Kuiti hospital manager Thia Priestly said there had so far been no admissions of people who were sick after being exposed to the contaminated water.
- NZPA
