The Round Rock City Council unanimously passed the first reading of a change in its water rate schedule that officials say they hope will push greater conservation.

The new four-tiered rate schedule would raise rates for the heaviest users from May to September, when usage is at its highest. Round Rock Utilities Director Michael Thane said the top 16 percent of residential users accounted for 42 percent of the residential water use in the city.

"That top 16 percent really needs to conserve, because that is really impacting our conservation," Thane said.

Rates would stay the same for users who stay under 24,000 gallons per month, but would rise with water use exceeding that amount. The schedule would be as follows during peak months (based on a 5/8-inch meter, the typical residential meter):

• First tier: $2.35 per 1,000 gallons for consumption between 0 and 18,000 gallons
• Second tier: $2.94 per 1,000 gallons for consumption between 18,001 and 24,000 gallons
• Third tier: $3.53 per 1,000 gallons for consumption between 24,001 and 30,000 gallons
• Fourth tier: $4.70 per 1,000 gallons for consumption greater than 30,001 gallons

Current rates are $2.35 per 1,000 gallons up to 18,000 gallons and $2.94 per gallon above that. Rates during off-peak months will remain at $2.35 per 1,000 gallons.

Thane said the hope is that the new pricing schedule will result in a 15 percent to 20 percent decrease in usage.

Though the council voted unanimously, several council members expressed some reservations about increasing rates for any users.

"I don't like this, but I would certainly be hypocritical if I didn't support this," Councilman Joe Clifford said, saying he saw the need for conservation even if he wasn't happy with raising some rates.