While city agency planners were figuring out how to cope with water shortages should they occur, the Metropolitan Washington Council of Governments was trying to raise area residents' water consciousness - the next best thing to raising the water tables.

"Our open house is usually in August," said Harry Ways, director of the Dalecarlia Water Treatment Plant for the U.S. Army Corps of Engineers. This year though, COG wanted the waterworks open before summer began, he said. The idea is to make people think about how to conserve water before peak use and low flow make that feared head-on-collision.

Demand from the Dalecarlia Reservoir, one of two major water treatement plants in the city, climbs from an average of 170 to 190 million gallons a day during the winter to about 280 gallons a day during the summer.

Last Saturday, with no cloud in the sky, visitors moved past tables of literature about how to conserve water, posters featuring photos of camels and educational displays about turbidity, eutrophication and flocculation, to tour the Dalecarlia plant.

The water starts out in a large earthen pond, the raw water impoundment area, where it starts for abour a day and a half.Then it comes churning into the plant to be mixed with a variety of chemicals to purify it and to neutralize other chemicals.

Visitors moved past green walls full of dials that monitor the quantities of various chemicals, past a lab full of running spigots where water quality is double-checked against what the dials say about it and past deep, dark ponds of water in a cool green room, where water is filtered through sand, gravel and coal to trap impurities.

The same process goes on in the adjoining room, the nicest part of the plant. Built in 1926, the water passes through rapid sand filters in octagonal pools which stretch across a white-columned room with a brick floor. Light streams in through a wall full of windows at one end of the room where potted plants are clustered. Inside, a pigeon swooped across the pools.

Visitors filed through the doorway outside to flocculation pools. Aluminum sulphate, a coagulant, is added to the water. It forms fluffy, cotton-like masses that collect impurities from the water and settle to the bottom - flocculation.

From the flocculation ponds visitors toured the organics lab, where the water treatement people test for heavy metals, pesticides and chloroform, and the microbiology lab, where they test for gas, coliform bacteria and other undersired additives.

Tour guide Donald De Haven, chief of the laboratory unit for the plant, had these insights to offer about water treatement during the tour:

A daily sample of water is taken from taps throughout the city.

In the past four years the coliform bacteria count in the Potomac River has dropped dramatically,

The electric bill for the water treatment plant is about $1.5 million. They have no generators of their own, but have never been without electricity for a significant period.

Many of the questions from visitors had to do with the treatment of water with chlorine because of recent reports that chloroform, created whn chlorine reacts with nutrients in the water, has been found in levels higher than the Environmental Protection Agency's suggested maximums in some water systems. Chloroform is suspected of causing cancer.

"The chlorine added is the bare minimum we can add to purify the water," said Ways. "We're in good shape for water quality," he said. "Quantity is the problem."