Everyone's health depends on it, but as events in Havelock North in 2016 showed, drinking water can also be a health hazard.
A major outbreak of gastroenteritis, associated with a campylobacter infection in Havelock North's bore-fed water supply, resulted in 5000 people falling ill. It was linked to the deaths of three elderly people.
A two-stage government inquiry was ordered into the outbreak.
One of its recommendations was that district health boards, their public health units, the Ministry of Health and local authorities should join forces to oversee drinking water quality.
The Southern District Health Board has acted on that, and last month the Southern Drinking Water Reference Group - encompassing seven territorial authorities and two regional councils with responsibility for over 200 registered water supplies - held its first meeting.
''It makes sense on many levels that we should have a strategic group looking at the quality of drinking water,'' Public Health Unit clinical leader Keith Reid said.
''Issues rural councils in particular face are similar, and there is an opportunity to share learning and solutions ... from our point of view it's important because we have oversight of the whole health district, which means a large number of water suppliers.''
As well as the 200 registered water supplies there are also a large number of unregistered schemes - Dr Reid estimated as many as 25,000 southerners could be getting their drinking water from such sources.
Crown Research Institute ESR collates drinking water quality information, noting the compliance of each source with bacteria, protozoa (which cause conditions like dysentery) and chemical level standards, and recording whether the quality of the water is graded or not.
Quality varies across the Southern region: perhaps unsurprisingly, the bigger population centres tend to do better while more sparsely populated areas with smaller rating bases can struggle.
Invercargill gets A ratings, a grade Dunedin mostly achieves barring some issues with bacteria issues in East Taieri, and Mosgiel being graded B.
The Lakes District faces challenges, with both Queenstown and Wanaka having ungraded water supplies which have recorded protozoa issues.
The Waihemo and Riverton water supplies have also faced protozoa issues.
In Central Otago, drinking water supplies at Alexandra, Clyde and Cromwell were all graded E, with each - as well as several smaller supplies - also having protozoa problems.
The Balclutha scheme was also battling to provide top-quality water, striking issues with protozoa and chemical contamination.
''Protozoa is an issue in many rural areas, and it's an issue particularly where surface water [lakes, rivers] is used as the main water source,'' Dr Reid said.
''It is an ongoing point of discussion between drinking water providers about the best way to manage protozoa compliance.''
In many cases, that would involve protecting the quality of source water - something dependent on land use in catchment areas.
However, not every council can afford the infrastructure or the staff required to monitor water quality.
''There has been discussion around technical staff [and] the lack of technical staff and how we might share access to expertise across the district,'' Dr Reid said.
''The way it works at the moment is that each council is contracting individually for testing and compliance. Then we as the health district have the drinking water assessors who sit across the top of that in terms of monitoring water safety plans and development and implementation and monitoring compliance with the drinking water standards and regulations on an operational basis.''
Infrastructure planning came as a pleasant surprise for Dr Reid, who expected to be told by councils they had not set aside money to build water treatment facilities.
''My expectation was that the challenge of capital expenditure for councils would be top of the agenda ... but the message we got from councils was that they were all committed to this and that they had all identified in their long-term plans money to invest in drinking water infrastructure.''
However, timing would be a challenge: larger councils could call on resources now, while smaller councils would need to phase in the introduction of new plant.
The next quarterly meeting of the group will be scheduled when the Government makes its formal response to the Havelock North inquiry, so it can then follow up any specific actions required.
The shadow of the 2016 outbreak looms large over the group's work - no territorial authority wants to be the next one dealing with a Havelock North-type situation.
''I think I can comfortably say I don't think we would see an outbreak on the same scale as Havelock North,'' Dr Reid said.
''That's because we don't have the same reliance on secure bores as a source to major population centres in our district. Where communities here are relying on bores, they are generally much smaller than Havelock North.
''There is the opportunity for a contaminated bore situation to arise in this district, but it would be of a much smaller magnitude than what we saw at Havelock North ... and I don't think we should be at all complacent about that.''
The lesson to be learnt from Havelock North was that drinking water could become contaminated unless standards were applied with rigour, Dr Reid said.
''You can't rely on the safety of the source as your only control measure,'' Dr Reid said.
''You need to have multiple barriers in place between the source and the consumer to provide the appropriate level of protection, and you need to be constantly vigilant about the quality of the water you are supplying,''
