Water pressure and your shower in Central Ohio: what the code asks, what the utilities publish
A shower that runs weak and a shower that hammers are both pressure questions, and the plumbing code answers them with numbers: a minimum flow pressure at the valve, a maximum flow at the head, and a ceiling above which the pressure inside a house must be brought down. This page sets out those sections of the Ohio Plumbing Code as they stand in September 2026, and beside them the pressures that Central Ohio utilities publish about their own systems, each in the utility's own words. Only a gauge at the house says what one address actually has.
Last updated September 2026 · Code sections are the Ohio Plumbing Code, the 2021 International Plumbing Code as Ohio adopts it, and utility statements are each utility's own, read September 24, 2026 · No prices on this page; the Estimate Builder carries those · Part of the knowledge base
What the code asks of a shower
Ohio's plumbing rule for water supply, rule 4101:3-6-01 of the Administrative Code, adopts chapter 6 of the International Plumbing Code, 2021 edition, and then amends it section by section; none of its amendments touches section 604, the one that sets pressures and flows, so the model code's section 604 is Ohio's. It states its minimums as flow pressure at a fixture's supply outlet under conditions of peak demand, in Table 604.3, and its ceiling as static pressure within the building, in section 604.8.
| What it covers | What the code requires | Where |
|---|---|---|
| Shower with a balanced-pressure, thermostatic or combination mixing valve | 2.5 gallons a minute at 20 psi flow pressure, or the valve maker's lower flow rating | Table 604.3 and its footnote b |
| Shower, other | 2.5 gallons a minute at 8 psi flow pressure | Table 604.3 |
| Bathtub with a balanced-pressure, thermostatic or combination mixing valve | 4 gallons a minute at 20 psi flow pressure | Table 604.3 |
| Shower head, including a hand-held shower spray | Not more than 2.5 gallons a minute at 80 psi | Table 604.4 and its footnote a |
| Supply pipe to a single-head shower | Not smaller than one-half inch | Table 604.5 |
| Pressure inside the building | A pressure-reducing valve with strainer where static pressure exceeds 80 psi, set to not greater than 80 psi | Section 604.8 |
| Pressure too low | A water pressure booster system where the supply cannot provide the Table 604.3 flow pressures | Section 604.7 |
Two further rules frame the table. Section 604.6 says that where street water main pressures fluctuate, the building's system shall be designed for the minimum pressure available, so a house is sized for its worst hour rather than its best. And the footnote to Table 604.3 matters in a remodel: where the shower mixing valve's manufacturer gives a lower flow rating than 2.5 gallons a minute, the lower value applies. What the valve types are, and the federal limit on a shower head sold today, are on the page on shower valves and fittings.
What Central Ohio utilities publish about their pressure
Few utilities print a number. The table gives every published statement found for this page, each read in the utility's own page or document; for any other system, the utility serving the address is the one to ask.
| Utility | What it publishes | Where |
|---|---|---|
| Del-Co Water | "Historically Del-Co has provided pressures within 40 – 100 PSI"; separately, it says the static pressure in its system ranges from 35 to 100 PSI and depends on the customer's elevation | Del-Co's Water Pressure and Selecting a Service Line pages, undated |
| Jefferson Water and Sewer District | "Water pressure in Jefferson Township ranges from 45psi - 105psi, depending on the location within the district." | The district's frequently asked questions page, undated |
| City of Marysville | "Minimum pressure at meter shall be 35 psi," and the normal working pressure in the waterline "will not be less than 35 PSI" | Water Division Specifications, updated March 2023, and Water Line Notes, effective March 1, 2023 |
| City of Dublin, on Columbus water | The system "is desired to maintain an operating pressure of 35 psi during normal daily demands and a minimum of 20 psi during fire-flow scenarios" | Envision Dublin Community Plan, adopted July 2024, chapter 9, Utilities |
| Aqua Ohio | "The customer shall be responsible for installing a pressure-reducing valve in high pressure areas," installed at initial construction "when the static pressure exceeds 80 p.s.i." | Summary of Aqua Ohio Service Line Standards |
Read against the code, two of those ranges run past its ceiling. Del-Co's published static range reaches 100 psi and Jefferson Township's published range 105, both above the 80 psi static level at which section 604.8 requires a pressure-reducing valve inside the building, and Aqua Ohio puts the valve on the customer in high pressure areas. At the other end, the 35 psi figures Marysville and Del-Co print as minimums, and the 35 psi Dublin's 2024 community plan wants during normal daily demand, with 20 psi as its minimum while water is drawn for a fire, describe the utility's system at or before the meter, before a house's own piping and fixtures take their share. A pressure-reducing valve also closes a house's water system, which is why the page on hot water for a Central Ohio shower sets out the thermal expansion rule that follows it.
What none of this says about a house
Scope, plainly. A utility's range covers a whole system, and Del-Co says in as many words that static pressure depends on elevation and cannot be changed. The code's numbers are requirements for how a system is designed and built, not a measurement of any house. What one address has is found with a gauge on a faucet or a call to the utility, and why a shower on a private well can run weak is a different question, answered on the page on wells and septic systems.
The short version. The Ohio Plumbing Code, the 2021 International Plumbing Code with no Ohio change to its pressure section, requires 2.5 gallons a minute at 20 psi flow pressure at a shower with a balanced-pressure or thermostatic valve, caps a shower head at 2.5 gallons a minute at 80 psi, and requires a pressure-reducing valve wherever static pressure inside a building exceeds 80 psi. Del-Co publishes a static range of 35 to 100 psi that depends on elevation, Jefferson Township a range of 45 to 105, and Marysville a 35 psi minimum at the meter; Aqua Ohio makes the pressure-reducing valve the customer's job above 80 psi.
Sources
Every figure, date and quotation on this page comes from one of these documents, read on the date given. Where two of them disagree, the page says so.
- Ohio Administrative Code (Ohio Board of Building Standards), Rule 4101:3-6-01, Water supply and distribution (Ohio Plumbing Code, Chapter 6), effective October 15, 2025; read September 2026.
- International Code Council, 2021 International Plumbing Code, Chapter 6, Water Supply and Distribution, section 604, read September 24, 2026.
- Del-Co Water, Water Pressure, undated; read September 2026.
- Del-Co Water, Selecting a Service Line, undated; read September 2026.
- Jefferson Water and Sewer District, Frequently asked questions, undated; read September 2026.
- City of Marysville, Water Division Specifications, updated March 2023; read September 2026.
- City of Marysville, Water Line Notes, effective March 1, 2023; read September 2026.
- City of Dublin, Envision Dublin Community Plan, chapter 9, Utilities, adopted July 2024; read September 25, 2026.
- Aqua Ohio, Summary of Aqua Ohio Service Line Standards, undated; read September 2026.
Common questions
What water pressure does a shower need under the Ohio plumbing code?
Under Table 604.3 of the 2021 International Plumbing Code, which Ohio adopts without changing its pressure section, the supply to a shower with a balanced-pressure, thermostatic or combination mixing valve must deliver 2.5 gallons a minute at a flow pressure of 20 psi under peak demand, or the valve maker's lower flow rating where it gives one. A shower without such a valve needs 2.5 gallons a minute at 8 psi. Where the supply cannot meet those, section 604.7 requires a booster system.
What water pressure does Del-Co Water deliver?
Del-Co Water says it has historically provided pressures within 40 to 100 psi, following the Recommended Standards for Water Works, and on a separate page that the static pressure in its system ranges from 35 to 100 psi, depends on the customer's elevation, and cannot be changed. Those are system-wide ranges; the pressure at one address is found with a gauge or by asking the utility.
Does a Central Ohio house need a pressure-reducing valve?
Where the static water pressure inside it exceeds 80 psi, yes: section 604.8 of the plumbing code Ohio adopts requires an approved pressure-reducing valve with a strainer to bring the building piping down to not more than 80 psi static. Del-Co publishes a static range reaching 100 psi and the Jefferson Water and Sewer District a pressure range reaching 105, so some addresses on those systems are above the line and some are not; only a gauge at the house says which.
Who is responsible for a pressure-reducing valve on Aqua Ohio water?
The customer. Aqua Ohio's summary of its service line standards says the customer shall be responsible for installing a pressure-reducing valve in high pressure areas, and that these valves should be installed at the time of initial construction when the static pressure exceeds 80 psi. That matches the plumbing code's own 80 psi threshold in section 604.8.
What is the water pressure in Jefferson Township, Ohio?
The Jefferson Water and Sewer District says water pressure in Jefferson Township ranges from 45 psi to 105 psi, depending on the location within the district, and gives a phone number for the pressure at a specific property. The top of that range is above the 80 psi static level at which the plumbing code requires a pressure-reducing valve inside a building.
What is the maximum flow for a shower head in the Ohio plumbing code?
Table 604.4 of the 2021 International Plumbing Code, which Ohio adopts, limits a shower head to 2.5 gallons a minute at 80 psi, and its footnote says a hand-held shower spray is a shower head. Table 604.5 sets the smallest supply pipe for a single-head shower at one-half inch. The design table, 604.3, asks for that same 2.5 gallons a minute at the shower's supply outlet.
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