Two government agencies are now recommending turning hot water heater thermostats down to about 120 degrees for energy conservation and safety.

Owners of automatic dishwashers might not be happy with the results.

President Carter's energy saving plan specifies that hot water supplies in public buildings be no warmer than 105 degrees. There are exceptions such as hospitals, restaurants and other buildings where hotter water is needed for sterilization or other reasons of health.

The rules say nothing about home hot water heaters. But the Department of Energy suggests that consumers turn their water heater thermostats to 120 degrees f.

"That setting is good enough for laundry and dishwashers, particulary if you use cold water detergents," a Doe spokesman said.

It would save considerable energy if everyone followed the DOE advice. Hot water heaters are believed to use the energy equivalent of 1.1 million barrels of oil daily.

The Consumer Product Safety Commission recomends a water temperature range of 120 to 125 degrees to protect against accidental scalding.

The commission's interest arises from a petition filed last year by Seattle City Light -- that city's electric utility. The petition said the scald proble was so bad the government should require all home water heaters to be designed so they could be set no higher than 130 degrees.

The utility said some heaters are pre-set at 150 degrees by their manufactures, and that water at that temperature will burn adult human skin in two seconds. At 130 degrees it takes 30 seconds for a similar burn.

The commission rejected the Seattle petition earlier this year but launched an educational compaign to alert the public to the daanger of scalds.

The commission suggests that consumers experiment with lower settings until they reach a temperature warm enough to wash dishes and clothes properly and provide enough hot water for their household needs.

A spokeswoman for Lever Brothers, a soap and detergent manufacture, warns that 120 degrees "is far too low for washing dishes in an automatic dishwasher. Our recommendation for dishwashers is 140 degrees, and in terms of cleaning it's better even higher than that."

She said the water must be at least 140 degrees to melt grease and leave dishes spotless. She added that water from a heater set at 140 degrees probably cools to 130 by the time it reaches the dishwasher.

She said water temperature for washing clothes can be much more flexible, although for really dirty work clothes or the like a seting of 140 might be wise.

People with easy access to their hot water heaters might try turning the thermostat up an hour or so before doing the laundry or running the dish washer, them turning it back down afterwards.

Energy experts also suggest turning the water heater thermostat way down when you go on an extended vacation.