He said he rang council and was told of the notice.
In the past, a council worker would have dropped off a leaflet advising of the problem, but that hadn't been done this time, Bray said.
He said he was "a bit disappointed".
Shires Fruit and Vege Market owner Suresh Patel said someone from the council had rung him early on Thursday morning, but he had seen the post on social media.
He said his shop wasn't affected as such, except in drinking water.
The communication was a "sticking point" however, as some elderly residents might not have been aware.
Alison Amboy of Regent Cafe had also seen the post and was taking the precautions.
She said it was "a bit annoying" because it was another thing to add to the list of restrictions from Covid.
"It's just something we can get through."
A council communications officer said a precautionary notice had been issued following public health advice.
The supply was still being treated and council had tested for any trace of a bacterial contamination and the test results were negative.
"Normally, if we were to experience turbidity of this nature, council would stop taking water from the river and instead take solely from the impounded supply. As the Dannevirke supply is currently under repair this was not possible and council was instructed to issue a precautionary notice."
As the notice was issued on Wednesday afternoon, it was not possible to get it published in the newspaper and so council used all available channels, which were council website, Facebook, emails to organisations and a media release was sent out to local media and radio stations, the officer said.
On Thursday morning, council contacted food businesses, hairdressers and funeral directors, medical centres, rest homes and pensioner housing tenants as well as Grey Power, schools, kindergartens and early childcare centres connected to the supply.
Since it was a "precautionary" notice, it was not required for council to complete a letter drop, the officer said.
"If this had been a 'mandatory' boil water notice, the process for communication would have been much different and council would have completed a full letter drop to both businesses and residents.
"Due to the feedback from the community, council will ensure to conduct a review of the communication process for Precautionary notices and will report the results of the review back to the community."