Colleyville bills a home's sewer by looking back at three months of water use. The city's utility rates page says residential sewer volume is set from each customer's average monthly water use during December, January and February. "Where no preceding winter quarter average is available," the city bills sewer volume on a default of 9,000 gallons a month.
Because of that rule, the water a Colleyville household uses in those three winter months costs more per gallon than any water it uses in summer, sprinklers included.
Three months set the sewer line for the year
Colleyville explained the method in a city notice on winter sewer calculations. The city averages each household's consumption over December, January and February "to set residential sewer rates for the year," and repeats the calculation every year. The city picked those months because they give "a true picture of interior water use when water consumption is not impacted by outdoor water use such as filling swimming pools and lawn sprinkler systems."
"Winter averaging allows customers the opportunity to lower their monthly sewer bill by reducing water use during winter months and keeps the sewer charges consistent each month."
That line comes from the same city notice. The notice also says some homes see their wastewater charge drop or rise from one year to the next because of those three months.
For a residential account, July irrigation never touches the sewer side of the bill. Commercial and industrial customers are billed sewer on total water use every month. Residential customers are billed on the winter average.
The math on a winter gallon
New per-gallon rates take effect Jan. 1, 2027, under Ordinance O-26-2388, which the City Council passed on second reading Sept. 15, 2026. Water goes to $7.0011 per 1,000 gallons and sewer to $4.8044 per 1,000 gallons. Here is how those two rates apply to an extra 1,000 gallons used at different times of year.
- An extra 1,000 gallons in July costs the water charge alone, about $7.00. The sewer line doesn't change.
- An extra 1,000 gallons in January costs the same $7.00 for water. It also raises the three-month winter average by about 333 gallons, which adds roughly $1.60 to every monthly sewer bill.
- Over twelve monthly bills, that $1.60 adds up to about $19.22. The winter gallons cost about $26.22 in total, nearly four times the summer figure.
The same math applies to the 9,000-gallon default. At the 2027 sewer rate, 9,000 gallons comes to about $43.24 a month in sewer volume charges. A household whose winter average comes in at 5,000 gallons, as an illustration, would pay about $24.02. That gap is roughly $19 a month, or around $230 a year, decided entirely by three winter months.
Regional guidance points the same way for outdoor watering. Save Tarrant Water, the regional conservation campaign, says in its fall and winter watering guide that most fall and winter weeks in North Texas need no watering. It also says to turn sprinklers off when it is raining or freezing. The city's own winter notice tells residents to watch for "dripping faucets, leaking toilets, etc." during those months to keep the following months' sewer bills down. An irrigation timer still set to a summer schedule, or a toilet that runs all night, now costs a full year of sewer charges.
Why the per-gallon side is the one to watch
Colleyville splits its utility bill into two parts that answer to different bodies. According to the city's September 2026 council briefing, under Ordinance O-16-1996, adopted Nov. 15, 2016 on the advice of the Water and Wastewater Rate Advisory Committee, base rates recover the city's operating costs. Volumetric rates pass through what the Trinity River Authority charges. According to the city's water and wastewater page, treated water comes from the Tarrant County Water Supply Project, which the Trinity River Authority operates. Wastewater is treated at TRA's Central Regional Wastewater Treatment Plant. The two parts change on different calendars. New base rates show up on October bills, and new volumetric rates show up on January bills.
The January 2027 per-gallon change is modest. Sewer goes from $4.7853 to $4.8044 per 1,000 gallons, and water goes from $6.6587 to $7.0011. Most of the water increase sits in TRA's debt component, which rises from $2.7964 to $3.1388.
The years after that are a different matter. The September 2026 council presentation says that because of "debt issuances for regulatory mandates," TRA projects its water rates to rise 26.84% in FY2029, 20.76% in FY2030 and 8.55% in FY2031. It projects wastewater increases of 6.77%, 8.91% and 6.74% over the same three years. If those projections hold, compounding would leave TRA's water rate about 66% above its FY2028 level by FY2031, and its wastewater rate about 24% higher. When Community Impact covered the council discussion, it quoted Finance Director Cassie Smith: "They are proposing extremely large increases in the future."
Because Colleyville passes those costs through per gallon, a household's usage will matter more each year. That applies most of all to winter usage, which drives the sewer volume charge for the year.
The fixed side starts with the meter
The other part of the bill doesn't depend on behavior at all. Starting Oct. 1, 2026, the water base charge rose 13.6% at every meter size. The residential wastewater base went up $2.59 to $18.08, and the capital projects charge stayed the same. Both the water base and the capital projects charge rise with meter size. The council briefing describes meters of 1 inch and smaller as "the majority of the City's residential base."
| In-city meter size | Water base | Capital projects | Residential wastewater base | Fixed monthly total |
|---|---|---|---|---|
| 1 inch or less | $20.72 | $5.83 | $18.08 | $44.63 |
| 1.5 inches | $41.44 | $10.78 | $18.08 | $70.30 |
| 2 inches | $66.31 | $16.74 | $18.08 | $101.13 |
Those totals cover only water and sewer, before any gallons are billed. The city's rates page also lists a $14 monthly residential stormwater fee and a $23.89 monthly garbage and recycling charge, effective Nov. 1, 2025. Two homes on similar lots can carry fixed charges that differ by more than $56 a month if one has a 2-inch meter and the other has a 1-inch meter. A seller's utility history shows which size serves the property.
What this means for a home changing hands
The winter window opens Dec. 1, about four weeks after this post goes up. For a buyer, the timing of a closing can affect which number ends up on the sewer line:
- A closing before December puts the new household on the account in time for its own usage over December, January and February to shape the winter average.
- A closing after February means the account goes most of a year before the next winter quarter. Under the ordinance, the 9,000-gallon default applies wherever no preceding winter-quarter average is available.
- How the city handles an account that changes hands is a question for Colleyville utility billing, the office that confirms which average or default a new owner's bill will use.
For sellers, a home's utility bills are part of what a buyer looks at. A low, steady sewer line reflects careful winter use, and a high one can point to a leak or an irrigation timer nobody switched off.
This post is general information about the city's published rates and isn't legal or financial advice. Please confirm the billing details for your own account directly with the City of Colleyville.
Quick answers
Does filling a pool in summer raise a Colleyville home's sewer charge? For residential customers, no. Sewer volume comes from the December through February average, and the city chose those months because pool filling and sprinklers don't usually show up in them.
Who sets the per-gallon rates? The Trinity River Authority. Colleyville passes TRA's costs through in the volumetric rates and sets the base rates to cover its own operating costs.
Do customers outside city limits pay the same? Out-of-city water base charges are $4.00 higher than in-city charges at every meter size.
If you're selling in Colleyville this winter, carrying costs are part of what buyers weigh, including the meter size and winter sewer history behind your utility bills. Sophie Tel Diaz Real Estate can help you present those numbers clearly next to your home's value. Request a complimentary home valuation, and we'll go over both with you.
