Aug 04 2014Share

The Ins And Outs Of Business Water Bills

By Kathleen Ferris

A Phoenix baker, carwash owner or pastor can expect far higher water and sewer bills than a Phoenix homeowner.

The difference is not just the higher volume of drinking water going into their businesses. The city also charges more because of contaminants the city must clean from wastewater flowing out of businesses.


Here are some of the reasons Phoenix businesses pay more than homeowners for drinking water.

  • A business owner pays a fixed monthly charge based on the size of the business’s water pipe. Pipes carrying drinking water into commercial properties are bigger than the typical ¾-inch residential pipes. For example, a church needs a 1-inch-diameter line with a fixed monthly cost of $4.49. A small café needs a 1.5-inch line costing $5.57 each month and a carwash a 2-inch line costing $5.97 each month.
  • Phoenix businesses, like homeowners, pay for water by the unit. Each unit equals 748 gallons (or 100 cubic feet of water). The city charges only 38 cents per unit. Here’s the catch: That cheap rate only applies to the first six to ten units used each month, depending on the season. Few businesses can keep their water use under that cap. After that cap is reached, the cost of water delivery rises sharply, ranging from $3.44 per unit in the winter to $4.15 in the heat of summer.
  • The average monthly water bill is $101 for a church with a cafeteria, $334 for a café, and $1,170 for a carwash. The average monthly water bill for a homeowner is $38.

But that’s only the half of it. The city also charges a sewer service fee on wastewater flowing out of a business.


Phoenix doesn’t measure wastewater leaving a business. The city calculates a charge based on 90 percent of the amount of water entering a business (allowing 10 percent for consumption and evaporation). How much a business pays per unit (748 gallons) of wastewater depends on the amount of work it takes at the sewage treatment plant to clean up the contaminants in the wastewater.

Here are a few examples of why sewer service charges vary among businesses.

  • A church with a cafeteria would pay a sewer charge 30 percent higher than a church without a cafeteria. Once there’s food being prepared there also is grease from dishes and mops flowing down the drains that grease catchers miss. That makes wastewater more expensive to clean at the treatment plant and costs the church $2.41 per unit (748 gallons). The average monthly sewer charge for a Phoenix church with a cafeteria is $108. If a church doesn’t have a cafeteria the average charge drops to $75.
  • When food is prepared for customers who eat inside a restaurant or pastry shop, the cost of each unit (748 gallons) of wastewater discharged is $4.48 or twice the amount paid by the church with a cafeteria. That’s because the volume of grease that slips into the city’s sewer system is far higher. The average monthly sewer charge for Phoenix’s restaurants and bakeries is $497.
  • Everyone would expect a carwash owner to pay an enormous bill, but each unit of wastewater discharged costs only $1.95, about 40 percent of what a restaurant owner pays. Wastewater discharged from a carwash is easier to clean at the treatment plant. Despite the amount of water used by a carwash, the average monthly sewer charge for a Phoenix carwash is $428.
  • The average monthly sewer charge for a homeowner is $21.

Like other AMWUA member cities, Phoenix tiers its water and sewer rates to cover what it costs to provide reliable services, maintain its treatments plants and pipeline systems, and meet regulatory requirements. There is more information about water rates at the city of Phoenix website.

For 45 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit


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