What the supply pipes are made of in Central Ohio houses, by era
Open the wall behind a Central Ohio bathtub and the supply pipe in it was chosen by the decade the house went up: galvanized, copper, CPVC, polybutylene or PEX. This page sets out what each cited source says about its own material and its own era, what the Ohio Plumbing Code still accepts, where lead sits in a Columbus house and in the service line under the yard, and what the code says about burial depth, an outside wall, hot water and the shower valve. Nothing here is a claim about any particular house, and every figure is attributed to the body that published it.
Last updated September 2026 · Code sections, city counts and federal definitions were read September 2026 · No prices on this page; the Estimate Builder carries those · Part of the knowledge base
Why the pipe behind the tub decides how the day goes
The day a bathtub comes out, the wall behind it opens, and the first things in view are the shower valve and the two supply lines feeding it, one hot and one cold. What those lines are made of was settled by the decade the house went up, and the material decides what can be joined to it and whether the code will still take that pipe for new work.
This page is about the supply side only, the pipe that brings water to the valve. The drain, the trap and the pipe under the floor are the subject of the house drains page, and who holds the state plumbing license and who inspects the work is the subject of the code page. What is behind the wall beside the pipe, by era, is on the bathroom electrical page, and what is under the floor is on the floors and subfloors page. What the wall framing those pipes run through is made of, era by era, is on the building page.
One thing is worth settling before any section number appears, because it sends people to the wrong book. The Residential Code of Ohio has no plumbing fixture chapter of its own: its section 2501.1 incorporates the Ohio Plumbing Code and says that code shall govern the installation, testing and operation of the plumbing in the buildings it covers. Every section quoted below is therefore a plumbing code section.
The materials, by the era each source gives
Nobody publishes a count of what is in Ohio houses by decade, so the table below does not attempt one. Each row states what its own source says about its own material, with the publisher named. Only one identification test here comes from a source: Michigan's Department of Environment, Great Lakes, and Energy says a magnet will stick to galvanized iron pipe.
| Material | How to recognize it | The era the source gives | What the Ohio Plumbing Code allows today |
|---|---|---|---|
| Galvanized steel or iron | Michigan's environment agency says a magnet will stick to it. EPA describes it as iron or steel dipped in zinc to prevent corrosion and rusting. | Michigan's environment agency says it was commonly installed in homes built before 1970. The trade publication PHC Pros says galvanized iron was still the dominant plumbing material in American homes in 1959. | Galvanized steel pipe is still listed in both material tables, 605.3 for water service and 605.4 for water distribution. |
| Copper | Metal tube joined at soldered fittings. The City of Columbus says homes built before 1989 may have copper pipe joined with lead solder. | PHC Pros says copper piping had largely displaced galvanized iron by the 1980s. | Copper and copper alloy are listed in both tables. |
| CPVC | A rigid plastic pipe. The sources here date it rather than describe it, so no sight test is offered. | Lubrizol says the chlorination technology behind CPVC was patented in 1958, that the first field trials began in 1960 in an experimental home built by the National Association of Home Builders, and that commercial production started in 1962. | Listed in both tables, against the ASTM and CSA standards the code names. |
| Polybutylene | No sight test is offered here. HUD says it is no longer approved for water supply piping. | HUD's design guide describes it as a thermoplastic used for supply water plumbing from about 1978 to 1995. | It appears in neither table. |
| PEX | Plastic tubing. No sight test is offered here either. | HUD's design guide says PEX was first introduced in North America in 1984, and HUD writes that it was used first for radiant floor heating and only later for household water. | Listed in both tables, for water distribution and for water service. |
Two cautions about that last column. Listed in the table is not the same as commonly installed: it says what may be used, not what is. And polybutylene's absence from both tables is a code fact rather than a warning.
Three notes on those rows
Michigan's environment agency says galvanized pipe was an alternative to lead pipe for water supply service lines, and that older galvanized pipe, made before 2014, contains a higher percentage of lead in its zinc coating than pipe made for drinking water since. No Ohio agency states an Ohio-specific era for any of them, so the years in the table are national. The CPVC dates are Lubrizol's own account of its own material, and a trade account of the same history gives different years for two of the three, which is why the row names the manufacturer rather than printing a bare date. For copper, what matters more is the solder in its joints, which is the next section.
Polybutylene
A Tennessee appeals court records that Shell Oil Company and Hoechst Celanese Corporation took part in making and marketing a polybutylene plumbing system, that the Cox complaint was filed on June 13, 1995, and that the trial court's order of August 24, 1995 directed Cox Class members who wished to opt out of the settlement to file exclusion requests. That opinion says nothing about how the systems failed, so neither does this page. The failure stories in circulation were not found in a document that could be cited.
PEX
HUD reports survey figures from Home Innovation Research Labs putting PEX at ten percent of the single-family plumbing market in 1997, sixteen percent in 2002 and sixty-three percent in 2016. Those are national figures for single-family construction, not a count of what is in existing Central Ohio houses, and no Ohio breakdown was found.
On freezing, HUD's guide is more careful than the reputation. It says that when water-filled PEX freezes, the elasticity of the material lets it expand without cracking or splitting and return to its original size on thawing, where the pipe has room to expand along its length. The same guide adds that PEX inside a slab may not be able to expand evenly, and that PEX systems should not be intentionally subjected to freezing.
Lead: the service line, the solder and what Columbus counted
HUD writes that lead pipes were used in homes until the early twentieth century and that many American homes are still served by lead pipes. In Columbus the subject has two halves, and running them together is the usual mistake: the service line in the ground, and the solder in the joints of copper pipe inside the house.
The two halves of a Columbus service line
The City of Columbus says the water service line has two parts. The utility-owned portion extends from the water main to the curb stop, and the customer-owned portion runs from the curb stop to the meter inside the home. That is the city's policy for its own service area; a household on a suburban system or a private well divides the responsibility differently, and the supplier is the one to ask.
The city says it stopped allowing lead and galvanized water service lines to be installed in the mid-1960s. Its own two pages do not agree on the year: one says December 1963, for lead and galvanized lines, the other says 1964, for lead lines. Both are the city's own words, so both are printed here.
Columbus City Code Chapter 1119, in the city's summary of its own ordinance, declares lead water service lines, including galvanized lines requiring replacement, a public nuisance and prohibits repairing a lead service line, so such a line is replaced rather than patched. The city describes its replacement program as a citywide, twelve-year project, and gives two different finish years in two of its own documents, so no finish year is printed here.
What the city counted in April 2024
EPA required community water systems to develop and submit an initial service line inventory by October 16, 2024, with every line categorized as lead, non-lead, galvanized requiring replacement, or unknown. Galvanized requiring replacement is a term of art: EPA defines a galvanized line that way when it currently is, or ever was, downstream of a lead service line, and says a system that cannot show otherwise must treat it so.
The City of Columbus published its inventory as of April 2024, covering approximately 284,000 active service lines, in five categories: non-lead, 78,060; unknown non-lead, 88,722; unknown, 84,230; lead, 25,140; and galvanized requiring replacement, 12,500. The two unknown categories are the largest entries in the table, and more than half of the lines had not been identified as one thing or the other when it was published. No total is worked out here: the five counts and the city's own rounded figure do not agree exactly inside its own document.
On its public pages the city puts the same thing more roundly: about twenty percent of its water service lines may still contain lead components, or roughly 50,000 to 60,000 homes with a possible lead or galvanized service line. A Columbus water official quoted by WOSU in May 2025 said the city would not be surprised if it replaces between 55,000 and 60,000 lead pipes. The city also says there is no detectable lead in the treated water leaving its water plants or in the source water those plants use.
What lead free has meant, and when
The Safe Drinking Water Act, codified at 42 U.S.C. 300g-6, has barred the use of any pipe, solder or flux that is not lead free in the installation or repair of a public water system, or of plumbing providing water for human consumption, since June 19, 1986. The City of Columbus states the household consequence in its own words: homes built before 1989 may have copper pipe joined with lead solder.
Lead free has also not always meant what it means now, which is why a system soldered lawfully in 1990 can still hold lead at its joints. EPA records that before January 4, 2014 the term allowed solder and flux with up to 0.2 percent lead, and pipes and pipe fittings with up to 8.0 percent lead. The Reduction of Lead in Drinking Water Act, which EPA records as enacted on January 4, 2011 with a prospective effective date of January 4, 2014, changed the definition to no more than a weighted average of 0.25 percent lead across the wetted surfaces of pipes, fittings and fixtures, and the Ohio Plumbing Code carries the same figure at section 605.2.1. The solder number did not change with it: section 605.12.3 still defines lead free for solder and flux as a composition of 0.2 percent lead or less. Two numbers, for two different things.
Ohio then adds an exception worth knowing while choosing a valve. Ohio's own amendment to the plumbing code, rule 4101:3-6-01, exempts a list of items from the lead content limits, and the list includes tub fillers and shower valves. The same exception states that the potable water supply pipe serving the fixture is not itself exempt. That is a state amendment rather than federal law.
The outside wall and the frost line
Ohio Plumbing Code section 305.4 requires exterior water supply system piping to be installed not less than 6 inches below the frost line and not less than 12 inches below grade. The same section bars installing water, soil and waste pipe outside a building, in an attic or crawl space, or concealed in an outside wall, unless adequate provision is made to protect such pipes from freezing, by insulation or heat or both. That second rule is the code's answer to a supply line or a valve on a cold outside wall.
Look at the shape of the first rule. The depth is set relative to the frost line, and the state does not print a frost line. The Residential Code of Ohio's climatic and geographic design criteria table leaves the frost line depth column blank, and the footnote reads that the jurisdiction shall fill in the frost line depth column with the minimum depth of footing below finish grade. So the number that decides how deep a water line goes is a local one, set by the building department that covers the address, and no depth for any Central Ohio jurisdiction is printed here.
Hot water, pressure and the shower valve
The code caps how far hot water has to travel. Ohio Plumbing Code section 607.2 limits the developed length of hot or tempered water piping, from the source of hot water to the fixtures it serves, to 50 feet. Developed length is measured along the pipe, not straight across the house, so a run that doubles back counts every foot of its path. That is the code's own answer to why the hot water takes so long to arrive, and it is a real constraint when a bathroom moves or a second one is added.
The valve is section 412.3. An individual shower or tub and shower valve has to be a balanced-pressure, thermostatic or combination type with a means to limit the maximum setting of the valve to 120 degrees Fahrenheit, and the section says in-line thermostatic valves may not be used to comply with it. Separately, the Consumer Product Safety Commission urges all users to lower their water heaters to 120 degrees Fahrenheit. Those are two different controls landing on the same number: a limit stop inside the valve, and a setting on the tank. What the valve and fitting choices mean is on the valves page.
Pressure is the other half of how a shower behaves. Ohio Plumbing Code section 604.8 requires an approved pressure-reducing valve with strainer where water pressure within a building exceeds 80 psi static.
One question this page cannot answer: how much colder the cold water runs in January than in July. It is a fair question, because the mix at the valve is made of both, but no utility or agency statement of Columbus's tap water temperature was found, so no figure for the valve itself is given here. The water supply page has a US Geological Survey reading from one of the city's reservoirs, which runs far colder in winter than in summer, though that is a measurement in the reservoir and not at the tap. Where the city's water comes from, and what is measured before it reaches a main, is the subject of the water supply page; what that water does to glass and walls is on the hardness page.
What the open wall means for a conversion
For a short while during a tub-to-shower conversion the supply lines, the valve and the drain are all visible at once, and the material in the wall stops being a fact about the age of the house and becomes a practical question. Polybutylene is the clearest case, because the code's tables do not carry it. Galvanized is the opposite: still listed in both, and still in houses of a certain age.
The shape of a conversion is covered on the conversion page, and the older-house version of the same question, including what to do about pipe that is exposed once the wall is open, is on the Upper Arlington page.
The short version. The supply pipe behind a Central Ohio bathroom wall follows the decade: galvanized before 1970, by Michigan's environment agency; copper displacing it by the 1980s, by the trade publication PHC Pros; CPVC on Lubrizol's own dates from the late 1950s and early 1960s; polybutylene from about 1978 to 1995, by HUD; PEX in North America since 1984, also by HUD. Galvanized, copper, CPVC and PEX are still in the Ohio Plumbing Code's two water pipe tables; polybutylene is in neither. Lead sits in two places, the service line under the yard and the solder in older copper joints, and the City of Columbus publishes a count of the first.
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 4101:8-25-01, Plumbing systems (Residential Code of Ohio, Chapter 25), effective July 1, 2019; read September 2026.
- Michigan Department of Environment, Great Lakes, and Energy, Galvanized Service Lines, May 2019; read September 2026.
- United States Environmental Protection Agency, Final Lead and Copper Rule Improvements Technical Fact Sheet: Service Line Inventory and Replacement Requirements, October 2024; read September 2026.
- PHC Pros, A History of CPVC in Residential Plumbing, September 5, 2022; read September 2026.
- International Code Council, via UpCodes, Ohio Plumbing Code 2024, Chapter 6, Water Supply and Distribution, undated; read September 2026.
- City of Columbus, Understanding Lead and Drinking Water, undated; read September 2026.
- Lubrizol (BlazeMaster), History of BlazeMaster CPVC: From Invention in Our Labs to Growth Around the World, undated; read September 2026.
- United States Department of Housing and Urban Development, Partnership for Advancing Technology in Housing, Design Guide: Residential PEX Water Supply Plumbing Systems, November 2006; read September 2026.
- United States Department of Housing and Urban Development (HUD USER), Water Piping in the Home, September 10, 2018; read September 2026.
- Court of Appeals of Tennessee, via FindLaw, Tina Cox, et al. v. Shell Oil Company, et al., October 31, 2005; read September 2026.
- City of Columbus, Lead Service Line Replacement Program, undated; read September 2026.
- City of Columbus, Lead Service Line Removal Ordinance and Lead Service Line Replacement Program, one-page summary, April 2024; read September 2026.
- WOSU Public Media, Columbus making progress towards replacing more than 20,000 lead pipes, May 19, 2025; read September 2026.
- Office of the Law Revision Counsel, United States House of Representatives, 42 U.S.C. 300g-6, Prohibition on use of lead pipes, solder, and flux, undated; read September 2026.
- United States Environmental Protection Agency, Summary of the Reduction of Lead in Drinking Water Act and Frequently Asked Questions, December 19, 2013; read September 2026.
- 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, via UpCodes, Ohio Plumbing Code 2024, Chapter 3, General Regulations, undated; read September 2026.
- Ohio Administrative Code (Ohio Board of Building Standards), Rule 4101:8-3-01, Building planning (Residential Code of Ohio, Chapter 3), effective July 1, 2019; read September 2026.
- International Code Council, via UpCodes, Ohio Plumbing Code 2024, Chapter 4, Fixtures, Faucets and Fixture Fittings, undated; read September 2026.
- United States Consumer Product Safety Commission, Avoiding Tap Water Scalds, Publication 5098, March 2012; read September 2026.
Common questions
What kind of water pipe is in a Central Ohio house built in the 1960s?
Commonly galvanized, on the sources cited here, though nothing counts it house by house. Michigan's environment agency says galvanized piping was commonly installed in homes built before 1970, and the trade publication PHC Pros says galvanized iron was still the dominant plumbing material in American homes in 1959 and that copper had largely displaced it by the 1980s. A 1960s house therefore sits in the changeover between the two. A magnet settles the first question in a second, because that same Michigan agency says a magnet will stick to galvanized iron pipe. Galvanized steel is still listed in the Ohio Plumbing Code's water pipe tables today.
Does Columbus still have lead water service lines?
Yes, and the city publishes a count. The City of Columbus published a service line material inventory as of April 2024 covering approximately 284,000 active service lines: non-lead 78,060, unknown non-lead 88,722, unknown 84,230, lead 25,140, and galvanized requiring replacement 12,500. More than half of the lines were still unidentified when that table was published. On its public pages the city says about twenty percent of its service lines may still contain lead components, or roughly 50,000 to 60,000 homes with a possible lead or galvanized line. The city says there is no detectable lead in the treated water leaving its plants.
How can I tell whether my house has galvanized, copper, CPVC or PEX pipe?
One test here comes from a source. Michigan's environment agency says a magnet will stick to galvanized iron pipe, and EPA describes galvanized as iron or steel that has been dipped in zinc to prevent corrosion and rusting. That separates galvanized from everything else. Beyond it, the sources cited on this page date the materials rather than describe how they look, so no sight test for copper, CPVC, polybutylene or PEX is offered. The decade the house was built is the better first clue, and exposed pipe at the water heater or in the basement is where most people look first.
Is polybutylene pipe still allowed in Ohio?
It is not in the code's tables. The Ohio Plumbing Code lists acceptable materials for water service pipe and for water distribution pipe in two tables, and polybutylene appears in neither of them, while galvanized steel, copper, CPVC and PEX all do. HUD's design guide describes polybutylene as a thermoplastic used for supply water plumbing from about 1978 to 1995 and says it is no longer approved for water supply piping. That is the whole of what is stated here. This page carries no account of how polybutylene systems failed, because the documents read for it do not give one.
How deep does a water line have to be buried in Ohio?
The state code sets the depth against a number it does not print. Ohio Plumbing Code section 305.4 requires exterior water supply system piping to be installed not less than 6 inches below the frost line and not less than 12 inches below grade. The Residential Code of Ohio's climatic and geographic design criteria table leaves the frost line depth column blank, and its footnote says the jurisdiction shall fill in that column with the minimum depth of footing below finish grade. So the frost line depth is a local figure, set by the building department covering the address, and that department is the one to ask.
Why does hot water take so long to reach a bathroom, and does the Ohio code limit it?
The code does limit it. Ohio Plumbing Code section 607.2 limits the developed length of hot or tempered water piping, from the source of hot water to the fixtures it serves, to 50 feet. Developed length is measured along the pipe rather than straight across the house, so a run that turns and doubles back counts every foot of its path. The water standing in that run is what comes out first, and that is the wait. The rule matters most when a bathroom moves, when one is added, or when the water heater sits at the far end of a long house.
Does the Ohio plumbing code limit how hot a shower can get?
It limits the valve. Ohio Plumbing Code section 412.3 requires an individual shower or tub and shower valve to be a balanced-pressure, thermostatic or combination type with a means to limit the maximum setting of the valve to 120 degrees Fahrenheit, and it says in-line thermostatic valves may not be used to comply with the section. Separately, the Consumer Product Safety Commission urges all users to lower their water heaters to 120 degrees Fahrenheit. Those are two different controls landing on the same number: a limit stop inside the valve, and a setting on the tank.
Who owns the water service line in Columbus, the city or the homeowner?
Both, in two parts. The City of Columbus says the utility-owned portion of a water service line extends from the water main to the curb stop, and the customer-owned portion runs from the curb stop to the meter inside the home. That is the city's policy for its own service area; a household on a suburban system or a private well divides the responsibility differently, and the supplier is the one to ask. Columbus City Code Chapter 1119, in the city's own summary, declares lead service lines, including galvanized lines requiring replacement, a public nuisance and prohibits repairing a lead service line.
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