American Fork City Council members are hoping to convince residents to double their monthly water bill.

After deliberating for more than two hours Wednesday afternoon, council members decided the residential and commercial rates for the proposed $46 million citywide pressurized irrigation system.

Those rates will include a base rate of $14 per month per 9,000-square-foot lot, with an additional charge of $17.50 per additional 10,000 square feet of property.

If a bond to pay for the new system is approved by voters in November, the irrigation system would represent a new bill for residents.

Council members also decided to increase culinary rates both to encourage residents to hook into the new pressurized irrigation system and to make up for potential lost revenue when people on the new system begin to use less culinary water.

Culinary rates would increase from a base rate of $10 per month for up to 8,000 gallons to $13.85 a month for up to 6,000 gallons. Those who use more than 6,000 gallons a month would be charged extra fees beginning at $2 per thousand gallons and increasing incrementally to $3.50 per thousand gallons. The per-thousand-gallon fee is now 75 cents.

In addition, all residents will see their water bill increase $5 a month whether or not the pressurized irrigation system is approved by voters. That money will go toward the purchase of water from the Central Utah Project and will ensure a future supply of water.

All told, if voters approve the pressurized irrigation system their water bills are estimated to double, council members said. Residents who own irrigation water shares will get to keep their shares and will pay only half the cost of the pressurized irrigation rates.

If residents do not approve the irrigation system, their bills will more than double over time, though just how much they would increase, and when, was not immediately clear, council members said. That increase would come from the rising cost of treating water to bring it to drinking water standards. The pressurized system will be cheaper in the long run because, though there is an upfront cost to install it, residents would be using cheaper untreated water on their lawns.

All churches and schools, and businesses that use large amounts of water, would be required to tie into the new pressurized system, said Mayor Heber Thompson. Businesses with little or no landscaping would not be allowed to tie into the system but their culinary water rates will be increased additionally as a way of forcing those businesses to help pay for the pressurized system.

Residents will be given a choice of whether to tie into the pressurized system, Thompson said. The rates chosen by the city assume 85 percent of residents will tie in. If that goal is not reached, the rates would have to be increased.

The city must increase rates enough to cover payments over 25 years of the bond issue and operations and maintenance of the system, said John Schiess, an engineer contracted by the city to study how to pay for the system.

If approved by voters this fall, the irrigation system would be completed by 2011. The new rates would be phased in geographically as the system was installed between now and then.

The rates chosen on Wednesday do not include a portion of money that would go toward replacing the system as it wears out, eliminating the need to issue bonds in the future. The council had considered adding such money to the rates and could still, said Schiess.

This story appeared in The Daily Herald on page B10.