A measure that would require the water authority serving Montgomery and Prince George’s counties to test drinking water more frequently won a key approval Friday.

The measure, sponsored by Del. Tom Hucker (D-Montgomery), would require the Washington Suburban Sanitary Commission to test quarterly for various contaminants and post information on the test results on its Web site. Currently, the agency tests less frequently, Hucker said, and doesn’t regularly post lists of the contaminants detected.

The Prince George’s County House delegation unanimously approved the measure Friday. The Montgomery County House delegation approved it earlier. The support of the two House delegations is a key step toward the bill’s approval by the full General Assembly.

“This way they test routinely and get the results before the public, if there is a problem,” Hucker said before the delegation vote. WSSC, which posts an annual water quality report, did not oppose the bill.