Foxton's drinking water is shown as E grade by the Ministry of Health while being touted as A grade by the Horowhenua District Council.
The council said the ministry's E grade was out of date. A Ministry of Health spokesperson in Wellington said the council had not requested a review of the grade.
E grade indicates an "unacceptable level of risk", according to the government's Drinking Water for New Zealand website where the Foxton grading is displayed.
The website data is based on current drinking water standards and legislation.
Following an inquiry from the Horowhenua Chronicle about Foxton's water's grade, council last week deleted text from its website that referred to Foxton water as "compliant with its A grade status under the NZ Drinking Water Standards set by the Ministry of Health".
Council water and waste services manager Paul Gaydon said Foxton's water was compliant with A grade quality under a previous grading system to the current standards.
Mid Central Health's public health unit drinking water assessor team is the body that officially grades water for HDC.
Assessor Peter Wood said the assessors had not given Foxton water an A grade under the previous system.
"If [HDC is] saying it is A grade, they have done that assessment. We haven't," he said.
Mr Wood agreed the E grade was out of date for Foxton but said HDC had not asked for a regrade.
"We would expect to go through a grading process with them and would then officially release the new grade."
Mr Wood writes an annual report on Foxton's water. He said the upcoming report for 2015/16 would show Foxton water and water treatment complied with current standards.
The report does not include a grading.
The drinking water standards focused on health criteria. Aesthetics - the look of the water - had a much lower priority, Mr Wood said.
"From my perspective, aesthetics are really important because you may have water that meets all the safety requirements, but if people are not prepared to drink it they are more likely to try and find another source of water that we can't guarantee might be as safe," he said.
Meanwhile, Foxton Beach drinking water has a grade of Aa. It received that grade in November 2014 following a regrade by the Mid Central Health drinking water assessors.