Wells, septic systems and what a bathroom remodel changes in Central Ohio
Outside city water and a public sewer, the office that says yes to a bathroom project is a county health district, and the rules it applies are Ohio's own. This page covers who permits and inspects a septic system and a well in Delaware, Licking, Fairfield and Franklin counties, how Ohio sizes a septic system by bedroom, what a remodel does and does not change, what may and may not drain into the system, the setbacks that decide where an addition can go, and what the published measurements say about Central Ohio well water. It carries no count of the houses on wells or septic systems here, because no agency publishes one.
Last updated September 2026 · Rules and figures are the agencies' own, read September 2026 · No prices on this page; the Estimate Builder carries those · Part of the knowledge base
Who this page is for
This page is about the Central Ohio house that is on neither city water nor a public sanitary sewer. The water comes from a well on the property, and everything that leaves the bathroom goes to a sewage treatment system in the yard, which for most houses is a septic tank and a leach field. In this service area that is the rural part of Delaware, Licking and Fairfield counties and the Franklin County townships outside the sewered suburbs.
How many houses that is, nobody publishes. No state agency and none of the four county health districts publishes a count of the households on a well or a septic system here, so this page prints none. Nationally, the US Environmental Protection Agency says one in five US homes have septic systems; that is EPA's figure for the country, not for Ohio.
What changes outside those systems is who has to say yes: the office that reviews a septic system and a well is a county health district, and the rules it applies are the state's. City water is on the water supply page, the city's sewers on the sewers page, the pipe from a sewered house to the street on the lateral page, and the code that governs the plumbing inside any house on the code page. Which utility serves each town in the service area is on the providers page.
Who permits a septic system, and who inspects it
Ohio's rules say a sewage treatment system may not be installed, altered or operated without an approved permit from the board of health. That is rule 3701-29-06 of the Ohio Administrative Code, and it covers altering a system as squarely as installing one. The Ohio Department of Health says the same to homeowners in plainer words: the permit must be obtained before construction or repair begins, and the local county or city health district is the first place to contact.
The rules themselves are recent. Ohio's current sewage treatment system rules are Chapter 3701-29 of the Ohio Administrative Code, and twenty-three of its twenty-four rules took effect on January 1, 2015. The chapter's own published record carries prior effective dates of 1974, 1977 and 2007 on individual rules, so the rules the 2015 chapter replaced went back to the 1970s. Wells sit in a separate chapter on a separate clock: Ohio's private water system rules are Chapter 3701-28, and all nineteen of its rules took effect on January 1, 2020. The Ohio Department of Health says private water systems are regulated under sections 3701.344 to 3701.347 of the Ohio Revised Code and administered by the department and the local health districts together.
Four health districts cover the counties this site works in. The table is what each publishes about itself, read in September 2026; the reader's own district is the one that decides.
| County | Office | What its page says it permits or regulates | Operation permit interval where stated |
|---|---|---|---|
| Delaware | Delaware Public Health District | Reviews designs, inspects installations and issues operation permits for household sewage treatment systems | Five years for gravity systems with no mechanical parts; one year for mechanical and discharging systems |
| Licking | Licking County Health Department | An installation permit and an operating permit, both before a system is installed | Every year for off-lot discharging and drip irrigation systems; every five years for soil absorption systems |
| Fairfield | Fairfield County Health Department | New installations, replacements and alterations; it says any installation or alteration work requires a permit | Not stated on the page read |
| Franklin | Franklin County Public Health | The construction, alteration and abandonment of private water systems, and it regulates sewage systems | Not stated on the page read |
Two things in that table are worth reading twice. Ohio's rules let an operation permit expire at whatever interval the board of health sets and cap that interval at ten years, so two houses a county line apart can be on different clocks for the same kind of system. And Ohio's rules put every system installed or altered after January 1, 2015 into a local operation and maintenance program with owner education, so altering a system, not only installing one, is what pulls a house into the county's program. Separately from any county schedule, the US Environmental Protection Agency says the average household septic system should be inspected at least every three years and that tanks are typically pumped every three to five years.
How a septic system is sized, and what a bathroom changes
Ohio's rules size a household system by bedrooms, not by bathrooms and not by people. Rule 3701-29-11 sets the daily design flow at one hundred twenty gallons a day per bedroom, with a minimum of two hundred forty gallons a day. A three-bedroom house is designed for three hundred sixty gallons a day whether it has one bathroom or three.
Because the design flow is counted by bedroom, adding or replacing a bathroom does not by itself change the number the system was sized to. A tub-to-shower conversion, which takes out a tub and puts a shower in the same alcove, adds no bedroom, so the arithmetic does not move. That is what the sizing rule counts, not permission to leave the health district out of it.
Ohio's rules define a bedroom broadly: a room designed or used as a sleeping room, or any room that could reasonably be used or finished as one, as the board of health determines. The Delaware Public Health District publishes the concrete version of that test: any room with an egress window, a closet, at least seventy square feet and space for a door will be considered a bedroom. A finished basement room can therefore change what the system is designed for even though no fixture was added.
The counties ask directly. The Delaware Public Health District's addition and remodel application asks whether the project includes a bedroom or a room that may be classified as one, and whether the work will connect to the existing septic system. Another county may ask differently or not at all.
Two more provisions decide how far the question goes. Ohio's rules say a system already in operation before the 2015 rules is deemed approved if it is not causing a public health nuisance, so an older system is not made illegal by its age. The same paragraph of Ohio's rules says nothing in it prevents a required upgrade of an existing system when additional flows are being added or when substantial changes to the structure occur. Ohio's rules also make the board of health require a higher design flow where there is an indication the flows may be exceeded, and let it approve a reduction for conditions such as low-flow fixtures.
What may go into a septic system, and what may not
Ohio's rules forbid a sewage treatment system from receiving water from a roof, a foundation drain, a clear water sump or a swimming pool. That matters when a basement bathroom and a sump pump are planned together: the bathroom's waste goes to the system and the sump's water may not.
The same paragraph of Ohio's rules allows an appropriately sized system to receive brine discharge from a water softener, unless the manufacturer's product-specific approval, the permit issued by the board of health, or a failing-system repair prohibits it. So the softener question has a qualified yes for an answer, and the qualification lives in the system's own approval and its permit.
Ohio's rules also define gray water, and a shower is inside the definition: wastewater discharged from lavatories, bathtubs, showers, clothes washers and laundry sinks that does not contain food wastes, urine or fecal matter. The definition creates no exception. Ohio's rules send all of a house's sewage to an approved system unless a gray water recycling system has been separately permitted under rule 3701-29-17.
Ten feet, fifty feet, and the day a sewer arrives
Ohio's rules keep every component of a sewage treatment system at least ten feet from a building or other structure, a property line or right-of-way boundary, a driveway or other hardscape, a properly sealed well, and a utility service line or roadway. That is the rule an addition, a deck, a patio or a slab runs into, none of which touches the plumbing at all.
The same rule of Ohio's keeps every component of the system at least fifty feet from any water supply source. On a lot with both, that is usually the distance that decides where anything new can go.
And Ohio's rules end the arrangement when a public sewer reaches the house. A sewage treatment system may not be sited, permitted or installed where a sanitary sewerage system is accessible, and an existing system must be abandoned once sewer reaches the house. The rule leaves the board of health to weigh availability, local ordinances, technical feasibility, plant capacity and distance in deciding what accessible means. What the house connects to after that is the sewers page and the lateral page.
The well: the permit, the pumping test and the water test
Ohio's rules call a well a private water system, a category defined by size: a system serving fewer than fifteen service connections that does not regularly serve an average of at least twenty-five people daily for at least sixty days a year. A spring, a cistern, a pond and a hauled water tank are in it too. Ohio's rules say no person may construct, alter or seal a private water system without a valid permit from the board of health, which here means the same health district that handles the septic system.
The water itself is nobody else's to police: the US Geological Survey says water from domestic wells is not regulated by the federal Safe Drinking Water Act, and the Ohio Department of Health applies the federal drinking water standards to private systems as health-based guidance rather than as enforceable limits.
Two agencies give different testing advice. The Ohio Department of Health requires a water test when a system is built or altered under an open permit, and past that recommends that owners test a few parameters such as total coliform bacteria, E. coli, nitrates and arsenic on a regular basis, naming no interval. The US Environmental Protection Agency does name one: it tells private well owners to test annually for total coliform bacteria, nitrates, total dissolved solids and pH.
Ohio's rules require a pumping test on a new well to determine its sustainable yield in gallons a minute and to confirm the well has capacity for the expected daily demand. That number is a property of the well and the ground under it, measured before any fixture in the house has been chosen.
The record outlives the drilling. Ohio Revised Code section 1521.05 requires a well log to be filed within thirty days of the completion of construction, recording the formations passed through, the depths at which water was encountered, the static water level and the pumping tests. The statute names the division of water resources, while the Ohio Department of Natural Resources' own pages say its Division of Geological Survey archives the logs and has been collecting water well records since 1946. The logs go to that department either way.
What Central Ohio well water is like
Ohio EPA describes a narrow north-south band of Devonian shale running across central Ohio where well yields run from zero to five gallons a minute and, in Ohio EPA's words, hydrogen sulfide is frequently present, which causes water quality problems. That band separates the carbonate aquifers to the west from the sandstone aquifers to the east, and the carbonate units Ohio EPA names in this part of the state are the Columbus and Delaware Limestones.
What the water carries has been measured, though rarely recently and rarely county by county. A 1984 US Geological Survey study of a stream-aquifer system in southern Franklin County called the aquifer's water a very hard calcium bicarbonate water that is high in dissolved solids, with dissolved iron frequently above the drinking water standard of 0.3 milligrams per liter. The US Environmental Protection Agency publishes that iron level as a non-enforceable secondary guideline whose effects it lists as rusty color, sediment, metallic taste and reddish or orange staining. That study is forty years old and covers one part of one county.
In a 2016 report the US Geological Survey sampled 168 domestic wells in Licking County and found arsenic above ten micrograms per liter in 12 percent of them, about one in eight, with a maximum of about 44 micrograms per liter in two wells in the same township.
For hardness, the broad Ohio measurement that exists is of raw source water rather than of household wells. Ohio EPA's sampling gives a median total hardness of 450 milligrams per liter as calcium carbonate in Ohio's carbonate aquifers, against 352 in sand and gravel and 214 in sandstone, and Ohio EPA says most of the wells sampled are public water supply production wells. Central Ohio straddles all three: carbonate bedrock to the west, sandstone to the east, sand and gravel in the buried valleys. Read those as the ground before treatment. What the public systems deliver after softening is on the hardness page.
What all of this means for a shower
Weak flow at a shower on a well is usually the well or the pump rather than the shower. Ohio's rules define peak demand for a private water system by the estimated number of usable water fixtures running at full flow, or by the maximum pump capacity where the pump is what limits it, and they require the pumping test above to establish what the well can sustain. What the valve itself does is a separate subject.
The one bathroom change that measurably helps a septic system is using less water. The US Environmental Protection Agency says high-efficiency shower heads and shower flow restrictors help reduce water use. The sizing rule does not move when a tub becomes a shower, because the rule counts bedrooms, but a lower-flow shower head does reduce the volume the system has to treat.
A water softener is a household decision rather than a shower requirement, and on a well it is usually made for the water's own sake; Ohio's rules allow an appropriately sized system to take its brine, with the qualification above, and what hard water does to glass and to a shower head is the hardness page's subject. The permit question belongs to the county. A conversion inside an existing bathroom adds no bedroom, and bedrooms are what the sizing rule counts, but the board of health decides what counts as additional flow or a substantial change to the structure. The health district is worth a call before the work rather than after.
The short version. Outside city water and sewer a county health district permits and inspects both the well and the septic system, under Ohio Administrative Code Chapter 3701-29 for sewage, effective January 1, 2015, and Chapter 3701-28 for private water systems, effective January 1, 2020. Ohio's rules size a septic system at one hundred twenty gallons a day per bedroom, so a tub-to-shower conversion changes nothing the sizing rule counts, while a room that could be finished as a bedroom can. Roof and foundation water may never enter the system, softener brine may where the system is sized for it, and every part stays ten feet from a building and fifty feet from a water source.
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.
- US Environmental Protection Agency, Septic System Care and Maintenance (SepticSmart), undated; read September 2026.
- Ohio Laws and Administrative Rules, Rule 3701-29-06 | General provisions and prohibitions, effective January 1, 2015; read September 2026.
- Ohio Department of Health, Sewage Treatment Systems - Information for Homeowners, undated; read September 2026.
- Ohio Laws and Administrative Rules, Chapter 3701-29 | Sewage Treatment Systems, read as published in 2026; read September 2026.
- Ohio Laws and Administrative Rules, Chapter 3701-28 | Private Water Systems, effective January 1, 2020; read September 2026.
- Ohio Department of Health, Private Water Systems Program, undated; read September 2026.
- Delaware Public Health District, Sewage, undated; read September 2026.
- Licking County Health Department, Sewage Treatment Program, undated; read September 2026.
- Fairfield County Health Department, Sewage Treatment Systems, undated; read September 2026.
- Franklin County Public Health, Water Quality, undated; read September 2026.
- Ohio Laws and Administrative Rules, Rule 3701-29-09 | Site review and permits for STS installation and operation, effective January 1, 2015; read September 2026.
- Delaware Public Health District, Supplement to Ohio Department of Health Sewage Treatment System Rules 3701-29, effective January 1, 2015; read September 2026.
- Ohio Laws and Administrative Rules, Rule 3701-29-19 | STS operation and maintenance management, and system owner education, effective January 1, 2015; read September 2026.
- US Environmental Protection Agency, How to Care for Your Septic System, undated; read September 2026.
- Ohio Laws and Administrative Rules, Rule 3701-29-11 | Flow estimation and waste strength, effective January 1, 2015; read September 2026.
- Ohio Laws and Administrative Rules, Rule 3701-29-01 | Definitions, effective January 1, 2015; read September 2026.
- Delaware Public Health District, Procedures for Obtaining a Sewage Permit, January 2025; read September 2026.
- Delaware Public Health District, 2026 Addition/Remodel Application, revised January 6, 2026; read September 2026.
- Ohio Laws and Administrative Rules, Rule 3701-29-02 | Scope, responsibility for compliance, and applicability of rules, effective January 1, 2015; read September 2026.
- Ohio Laws and Administrative Rules, Rule 3701-29-17 | Gray water recycling systems and alternative toilets, effective January 1, 2015; read September 2026.
- Ohio Laws and Administrative Rules, Rule 3701-28-01 | Definitions, effective January 1, 2020; read September 2026.
- Ohio Laws and Administrative Rules, Rule 3701-28-03 | Permits, system approval and sampling requirements, effective January 1, 2020; read September 2026.
- US Geological Survey, Domestic (Private) Supply Wells, March 2019; read September 2026.
- Ohio Department of Health, Private Water Systems - Water Quality, undated; read September 2026.
- US Environmental Protection Agency, Protect Your Home's Water, undated; read September 2026.
- Ohio Laws and Administrative Rules, Rule 3701-28-11 | Development, startup, and operation of new, repaired and altered wells, effective January 1, 2020; read September 2026.
- Ohio Laws and Administrative Rules, Section 1521.05 | Well construction logs - well sealing reports, effective January 1, 2016; read September 2026.
- Ohio Department of Natural Resources, Information for Water Well Owners, undated; read September 2026.
- Ohio Environmental Protection Agency, Major Aquifers in Ohio and Associated Water Quality, October 2015; read September 2026.
- US Geological Survey, Water quality of a stream-aquifer system, southern Franklin County, Ohio (WRIR 84-4238), 1984; read September 2026.
- US Environmental Protection Agency, Secondary Drinking Water Standards: Guidance for Nuisance Chemicals, undated; read September 2026.
- US Geological Survey, Arsenic in Groundwater of Licking County, Ohio, 2012 - Occurrence and Relation to Hydrogeology (SIR 2015-5148), 2016; read September 2026.
Common questions
Who issues septic system permits in Delaware, Licking, Fairfield and Franklin counties?
The county health district, not a building department. Ohio's rules say a sewage treatment system may not be installed, altered or operated without an approved permit from the board of health, and the Ohio Department of Health tells homeowners that permit must be obtained before construction or repair begins. In these four counties the offices are the Delaware Public Health District, the Licking County Health Department, the Fairfield County Health Department and Franklin County Public Health. Each publishes its own program, and the published operation permit interval differs between them, so the county an address sits in decides the details.
How many gallons a day is an Ohio septic system designed for?
By bedroom. Ohio's rules set the daily design flow for a household sewage treatment system at one hundred twenty gallons a day per bedroom, with a minimum of two hundred forty gallons a day, so a three-bedroom house is designed for three hundred sixty gallons a day whether it has one bathroom or three. Ohio's rules also make the board of health require a higher design flow where there is an indication the flows may be exceeded, and let it approve a reduction for conditions such as low-flow fixtures. Bedrooms, not bathrooms and not people, are the unit.
Does a tub-to-shower conversion change the size of a septic system in Ohio?
Not the sizing arithmetic. Ohio's rules count design flow by bedroom, at one hundred twenty gallons a day for each one, so taking out a tub and putting a shower in the same alcove adds no bedroom and changes nothing the rule counts. That is not the same as saying the health district has no interest. Ohio's rules preserve a required upgrade of an existing system when additional flows are being added or when substantial changes to the structure occur, and the board of health decides what counts. The Delaware Public Health District's addition and remodel application asks about both.
Does finishing a basement room count as adding a bedroom for a septic system in Ohio?
It can, and it is the change most likely to matter. Ohio's rules define a bedroom as a room designed or used as a sleeping room, or any room that could reasonably be used or finished as one, as the board of health determines. The Delaware Public Health District publishes the test it applies: any room with an egress window, a closet, at least seventy square feet and space for a door will be considered a bedroom. Whether anyone sleeps there is not the question, and because a system is sized by bedroom, a finished room can change what it is designed for.
Can a water softener drain into a septic system in Ohio?
Usually yes, with a condition attached. Ohio's rules allow an appropriately sized sewage treatment system to receive brine discharge from a water softener, unless the manufacturer's product-specific approval, the permit issued by the board of health, or a failing-system repair prohibits it. The same paragraph is flat about what may never go in: no water from a roof, a foundation drain, a clear water sump or a swimming pool may enter the system. So the softener question is answered by the system's own approval and its permit, and the sump question is answered by the rule itself.
How far does a septic system have to be from a house and a well in Ohio?
Ohio's rules keep every component of a sewage treatment system at least ten feet from a building or other structure, a property line or right-of-way boundary, a driveway or other hardscape, a properly sealed well, and a utility service line or roadway, and at least fifty feet from any water supply source. Those distances catch an addition, a deck or a patio that never touches the plumbing. The federal Environmental Protection Agency adds the operating version for the drainfield: do not build structures on it without checking with a local designer or permitting authority, and do not park or drive on it.
How often should a private well in Ohio be tested?
Two agencies answer differently, and both answers are worth having. The Ohio Department of Health requires a water test when a private water system is built or altered under an open permit, and past that recommends testing a few parameters such as total coliform bacteria, E. coli, nitrates and arsenic on a regular basis, without naming an interval. The United States Environmental Protection Agency does name one: it tells private well owners to test annually for total coliform bacteria, nitrates, total dissolved solids and pH. Water from a domestic well is not regulated by the federal Safe Drinking Water Act.
Why does a shower run weak on a well in Central Ohio?
Often because of the well rather than the shower. Ohio's rules define peak demand for a private water system by the estimated number of usable water fixtures running at full flow, or by the maximum pump capacity where the pump is what limits it, and they require a pumping test on a new well to establish its sustainable yield in gallons a minute. Ohio EPA describes a narrow north-south band of Devonian shale across central Ohio where well yields run from zero to five gallons a minute. A shower valve passes along what the well and the pump deliver.
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