Local power supplier Unison will conduct a review after this winter to see how it can communicate power demands after one Rotorua family reported cold-water showers most weeks this past month.
The hot-water shortage is a result of something called ripple relay, when power is diverted from hot-water cylinders to go on to the main network at peak demand.
A Unison spokesman said due to a colder than usual winter and more people using power for heat instead of wood, some families had been hit more than usual.
The Pargeter family of Ngongotaha thought they had timed the ripple relay correctly, but it kept changing.
"When it first happened I assumed I had a hot-water failure," Rhys Pargeter said.
"The next day I was going to check the plumbing under the house but when I woke up there was hot water. I was going to call a plumber and I fully expected to find puddles under my house."
He said he rang around and eventually got put on to Unison, which maintained the power network. He discovered the hot-water cylinder heating had been turned off about 5pm to avoid a power surge.
"But on Tuesday the boys got home at 4pm and went to have their showers and there was no hot water at all."
He said it might seem unimportant to some but, to have it happen three weeks out of four and on nights when they all needed showers from football trainings and work, it had become too much to handle.
"My main grizzle is it's not been communicated to us. We've not been able to plan around it.
"We have attempted to arrange our lives around their supposed schedule but, as this changes seemingly on a daily basis, can no longer make these arrangements acceptably and are faced with washing in the sink with jug-boiled water so as to have a hot wash at nights."
He said at first his two sons, aged 12 and 14, had cold showers but now visited family who had hot water for post-football showers.
"I've lived in Rotorua my whole life and this is the first time it's happened."
Unison customer-relations spokesman Danny Gough said hot-water cylinders were turned off across the network depending on how much power was required.
He said there were peak times, in the morning and evening, when people used their ovens, heat pumps, heaters and other electrical items.
"Most people should be fine but if it's a family they can run out of hot water, regrettably," Mr Gough said. "It's not a conservation programme but more about peaks. There is a certain capacity and it does put a strain on it. When it's under stress it can fail. It's a balancing act.
"In an ideal world people shouldn't notice it but this winter we've had to conduct more controlling than normal and it's come under the spotlight."
He said Unison would review the power usage and amount of controlling and decide whether it needed to communicate this with customers more next winter.
What is ripple relay?
* Hot-water cylinders are on separate power supply
* Unison can turn power off if peak demand is too high
* Peak demand is usually around 7-8am and 5-6pm
* Hot-water cylinders take 3-4 hours to reheat
* Unison customers across Rotorua and Hawke's Bay are affected
* Other power suppliers also operate controlling
* No way of knowing in advance