Why is my sewer bill higher than my water bill?

In a way, water is a lot like a two-way toll bridge… it costs us coming and going.  Turning lake, river, or ground water into safe drinking water has a cost.  Cleansing the resulting wastewater for its return to the environment has another cost.  Fortunately, the people of Huntsville pay lower rates than much of the State or the country for both drinking water and wastewater treatment service.

Whatever the costs, customers are sometimes surprised to find their sewer bill to be as much as, or even more than their water bill.  How can this be?  After all, drinking water is clean, pure, healthful.  Wastewater is, well… sewage.

Actually, it is not unusual across the country for a sewer bill to be higher than the corresponding water bill.  As environmental regulations have become more and more stringent over the past few decades, the costs of treating wastewater to required levels have risen substantially.

The relative sizes of a customer’s water bill and sewer bill depend on how various water and wastewater utilities calculate their bills.  Drinking water providers like Huntsville Utilities (www.hsvutil.org) ordinarily bill monthly based on the quantity of water metered plus a monthly service charge.  Huntsville Utilities’ current residential water rate (for City of Huntsville residents) is $3.39 service fee plus $1.15 per thousand gallons of water metered for the first 3,000 gallons, and $1.28 per thousand gallons thereafter.

Many providers of wastewater treatment services, like the Huntsville Water Pollution Control Department, also charge for their service based on the amount of drinking water metered - although some providers bill a flat monthly fee.  Basing a sewer bill on drinking water usage is simple logic: “what goes in must come out”.  In other words, water that goes into a home as drinking water is returned as wastewater.  The City of Huntsville’s single-family residential sewer service charge as of January 1, 2007 is $3.82 per thousand gallons of drinking water.

A typical family might use about 7,500 gallons of drinking water in a month.  The water bill from Huntsville Utilities for that usage would be $12.60.  The sewer bill from Huntsville Water Pollution Control Department for the same month would be $28.65.

Why?

Sewer charges are higher than water costs for many reasons.  The major reason lies in the differences between the systems for water distribution and wastewater collection.  Drinking water flows through pressurized pipelines.  It can move uphill as well as downhill.  This means that water pipelines can be constructed at minimum depth below the ground surface, often above the rock layers.  On the other hand, wastewater must flow by gravity – downhill the whole way.  In rolling terrain, sewer lines must sometimes be built deep beneath the ground, well into hard rock.  Trench excavation – especially in rock - is the largest part of the cost of building a pipeline.  The deeper the pipe, the higher the cost of construction.

Another cost factor lies in where the two types of pipelines can be built.  Since sewers rely on gravity to cause flow, they must be built in lower-lying areas so adjacent homes will be at a higher elevation.  Right-of-way must be acquired and cleared, adding to overall costs.  Water line locations however, are not restricted by the laws of gravity flow.  Water pipelines can be built in already-cleared road rights-of-way, often above the tough rock layers.  This construction is much easier and quicker.

The sizes of drinking water distribution and wastewater collection systems also affect costs.  Ordinarily, a community will serve more of its citizens with public drinking water than with sewer service.  Many water customers are on septic tanks instead of sewers.  The water utility has a larger customer base to support its operating costs, lowering the cost to individual customers.

Also figuring into the mix are the differences in  the treatment of drinking water and wastewater.  The fundamentals of making drinking water have changed little over the years: settle it, filter it, disinfect it.  That method produces high-quality drinking water in systems the world over.

The complexity of wastewater treatment, on the other hand, has increased dramatically over the years.  In its earliest form at the turn of the century, wastewater treatment (if it was provided at all) consisted of screening out the really big objects, then discharging the rest to a nearby creek.  Fifty years later came settling tanks to remove smaller solids… but the finished product remained terribly polluted, by today’s standards.  Over the last couple of decades, treatment has evolved to include sophisticated biological systems for removing organic materials, complicated filters, and modern disinfection methods.  The water released by the treatment facility is usually cleaner than the receiving stream!  The advanced systems are costly to build and operate, increasing the overall cost of wastewater treatment, in most cases.

The cost of treating wastewater has risen more dramatically than the cost of producing drinking water over the years.  So it is logical that sewer bills are higher than water bills.  Still, Huntsville’s residents enjoy better water and sewer rates than much of the country.  And in spite of our area’s comparatively low rates, we still enjoy the benefits of a well-run wastewater collection and treatment system - clean water resources and reliable sewer service.