Lawrence utility users will get a push to run their taps less if city leaders approve a new billing method that charges higher rates to those using large quantities of water.

At their work session Tuesday, city commissioners said the proposed method, which would charge the highest consumers of water 15 percent more, will encourage conservation.

“I think it’s definitely a value for the city of Lawrence: conservation, sustainability,” said Vice Mayor Leslie Soden.

The new billing method for water and waste water would also generate about 8 percent more revenue for the utilities department, which city staff said will help pay for infrastructure improvements. The commission indicated they would support a tiered rate model, which would go into effect in 2018. Any changes would be in addition to a 5 percent rate increase for all users that is going into effect next week.

The “block rate” billing model would create three different rates based on a customer’s level of consumption. Customers who use significantly more water per month than the average household would be charged 10-15 percent more. Low-consuming households and residents with low or fixed income would pay less under the new model.

The model would be for residential customers only. Each month would be a restart — meaning residents wouldn’t necessarily be locked into the higher rates — and only water used over the high-use threshold would be charged at the higher cost, according to Mike Lawless, assistant director of utilities for the city. Those who use water for irrigation would have other rates and require a separate meter and service connection.

The new model would replace the current billing structure, which doesn’t vary based on consumption and instead bills at different rates for different “classes” of customers. The current model charges a higher rate for single-family residential than multifamily residential, and Mayor Mike Amyx said the new model is more equitable.

“This is all about fairness,” Amyx said.

The commission will eventually choose between two different tiered models, one of which would result in more customers being charged the higher rates. Both models charge 10 and 15 percent more for the second and third tiers of users, but vary on what percentage of users are subject to the higher prices.

For both models — fixed inclining and individual inclining — the first tier of “average users” would not have a rate increase. The fixed method, under which 78 percent of users would not see an increase, uses a fixed number of gallons per month (5,000 gallons or fewer) to define who falls under the first tier. The individual method, under which 70 percent of users would not see an increase, uses a percent of average consumption (125 percent or less of winter consumption) to define who falls under the first tier.

Commissioner Stuart Boley said he was in favor of the fixed method because of its relative simplicity. Soden, Amyx and Commissioner Matthew Herbert indicated they were in favor of the individual method.

“Conservation and affordability were the direction we gave you last time, and that one seems to score the best on both,” Herbert told staff.

At the commission’s request, city staff have spent the past year and a half looking into alternatives to the current billing method. As part of Tuesday’s work session, staff also presented the utility department capital improvement plan, the scope of which will be dependent on the rate model decided upon by the commission.

The staff-recommended CIP for 2018 to 2022 is currently projected to cost $130 million. It includes projects such as Advanced Metering Infrastructure, the design of the Kansas River Waste Water Treatment Plant for nutrient removal, a field operations building and Bowersock Dam repairs.

If the commission decides to go forward with changes, the billing model would be developed and finalized as part of the commission’s 2018 budget considerations in the spring.