Thousands of central Auckland residents are waiting to learn whether their tap water is safe to drink after a routine water sample returned positive for E. coli.

Watercare, Auckland Council’s infrastructure asset management company, said it’s taking a “cautious approach” after yesterday’s positive result.

A “precautionary” boil water notice will remain in place as it continues testing and monitoring today.

Watercare issued the notice last night for 7800 properties across Hillsborough, Mt Roskill, Royal Oak and Three Kings after a single test showed traces of E. coli. About 40 tests are taken throughout the Auckland network each day.

All other results in the area were within normal ranges, Watercare said.

Three water tankers have been set up to support locals unable to boil their own tap water, and Watercare said it was encouraging to see “people who need to” are making use of them.

The water tankers are “well stocked” and will remain operating until the notice has been lifted, Watercare said.

Residents are asked to bring clean, secure containers for water collection.

Two are publicly available at 113 Duke St, outside Big King Reserve, and in Carlton St’s Hillsborough Park carpark.

A third water tanker has been brought in to supply residents at an unspecified retirement village.

Watercare’s activity appeared to be centred around Big King Reserve when the Herald visited both public water tanker sites this morning.

There was a steady drip of residents filling up their vessels or enquiring about the notice. Watercare vehicles and workers were stationed around the Duke St water pump station, or ascending the maunga to its on-site reservoir.

Watercare told the Herald its teams were “undertaking a range of precautionary measures” at Big King Reserve, such as water quality sampling, inspections of the reservoir, and inspections of network assets in the wider area.

“Crews are also walking streets and inspecting infrastructure as part of our investigations to identify any potential issues,” Watercare said.

“This work is continuing and will remain underway until the boil water notice can be safely lifted.”

Watercare workers could be seen inspecting the reservoir atop Big King Reserve this morning. 

Which areas are affected? 

The notice covers about 7800 homes and businesses around Hillsborough, Mt Roskill, Royal Oak and Three Kings. 

Not all streets in each suburb are affected, and Watercare has supplied the maps below for people to see if their property is included. 

Drinking water remains safe to consume outside the areas on the maps. 

At the time of issue, Watercare said there was “no evidence” of a region-wide problem and called the notice a “precautionary measure” in case residents fell ill while investigations were ongoing. 

Watercare has issued a boil water notice this evening for Hillsborough, Mt Roskill, Royal Oak and Three Kings. Image / Watercare 

Watercare has issued a boil water notice this evening for Hillsborough, Mt Roskill, Royal Oak and Three Kings. Image / Watercare 

What do people in the affected areas need to do? 

Residents in affected areas are being advised to boil tap water before drinking it or using it for food preparation. 

Boiled or bottled water should also be used for cleaning teeth, making ice, washing dishes and preparing food until further notice. 

Watercare said boiling water in an electric kettle once is enough to kill bacteria and other organisms, after which the water can be cooled and used normally. 

For people unable to boil their own water or buy bottled, Watercare’s public tankers provide safe drinking water. 

Watercare is operating public water tankers for affected residents until the issue of potential contamination is resolved. Photo / Michael Craig 

What is E. coli and are there any symptoms? 

E. coli is a group of bacteria commonly found in the intestines of people and animals. Most types are harmless, but some can cause illness or indicate the presence of other pathogens. 

E. coli can spread through contaminated food, including undercooked meat and raw milk, contaminated water, contact with people who are sick, and contact with farm animals, animal faeces, and soil. 

It can also spread easily from person to person if infected people do not wash their hands properly. 

Symptoms are often mild, but they can be more serious when young children, older people, and people with weakened immune systems are infected. 

Symptoms can include stomach cramps, diarrhoea - sometimes bloody, and nausea and vomiting. 

Most people get better within five to seven days. 

3D illustration showing Escherichia coli, E. coli, colonising parts of the intestine. Image / Getty Images