The order comes in the middle of a South Island heatwave, with predictions Invercargill could register its hottest-ever October day today.
Council water manager Alister Murray said residents in northern and eastern parts of Invercargill would experience lower than normal water pressures while the pump station was out of action.
"We do have problems with distributing water within the Invercargill network and also down to Bluff and are asking all consumers to make strenuous efforts to conserve water," he said.
"We need to move as quickly but as safely as possible to restore this essential service. We are very conscious that the hot weather would ordinarily mean higher than usual water consumption and in the meantime we are asking people to limit their water use until further notice," Murray said.