They hope to save up to 400 megawatts of electricity - equivalent to the output of an electrical power plant.
Blackouts have dogged Zimbabwe, despite the fact that 60% of the population have no access to electricity.
This has also hampered investment in what is an already fragile economy, the BBC`s Karen Allen reports.
Officials from the state-owned Zimbabwe Electricity Distribution and Transmission Company say the government is expected to publish new regulations by the end of the year.
It is estimated that there are up to 300,000 geysers across the country, with water heating accounting for some 40% of households` electricity bills.
"The country may achieve a power saving in the range of 300 megawatts to 400 megawatts, which in itself is a virtual power plant," Energy Minister Samuel Undenge was quoted as saying by Reuters.
"Solar water heaters (will) become mandatory at every new house before connection to the grid," he added.
Zimbabwe`s power generation is currently less than 50% of its peak demand, forcing local businesses to use costly generators.
The government has blamed the shortages on low water levels at the Kariba Dam, bordering Zambia, which generates hydroelectric power, the BBC`s southern Africa correspondent Karen Allen reports from Johannesburg.
But officials also concede that a massive lack of investment in the energy sector over the decades is now taking its toll.
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