Sewer line cleanout under construction (C) D Friedman Galow HomesBuilding Drain Cleanouts
Inspection, location, installation, use, repair of plumbing drain cleanouts

  • CLEANOUTS, PLUMBING DRAIN - CONTENTS: Guide to building plumbing drain cleanouts used to clear clogged drain piping. Where should drain piping cleanouts be located? Size, angles, access requirements for building drain pipe cleanouts. Where do we insert the plumbing snake to clear a clogged drain?
  • POST a QUESTION or READ FAQs about plumbing cleanouts

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Building drain cleanout access ports:

How to locate & use plumbing drain cleanouts: this article describes cleanouts used to access and clear clogged building drain pipes. Plumbing cleanouts are access points from which it is easiest to attempt to clear a slow or clogged drain line.

Our page top photo shows a main building drain cleanout at the location where it is most commonly found: where the building drain exits the structure.

Green links show where you are. © Copyright 2017, All Rights Reserved.

Guide to Finding & Using Building Plumbing Drain Cleanouts

Indoor Building Drain Cleanouts

Plumbing cleanout (C) D FriedmanAs we cited at DRAIN & SEWER PIPING, Plumbing codes define a building drain as "that part of the lowest piping of a building drainage system that receives the discharge from soil, waste, and other drainage pipes inside the walls [or upper floors] of the building and conveys it to the building sewer [or septic system] beginning two feet (0.6m) outside the building wall."

This piping and its horizontal branches are required to have cleanouts, however no cleanout is required for any pipe or piping above the first floor of the building.

Where do I Find the Plumbing Drain Cleanout for Upper Building Floors?

If you need to run a plumbing snake through drain piping through pipes above the first floor of the building you will most likely need to open a sink trap, shower drain, or remove a toilet to most easily access the larger-diameter drain piping on upper floors.

But most often plumbing drains clog at bends, elbows, tees, and in the longer horizontal runs often found on the first floor or between the building itself and the sewer line or septic system.

A Photo Guide to Plumbing Cleanouts & Cleanout Problems

Sewer line cleanout under construction (C) D Friedman Galow Homes

Our plumbing drain cleanout photo (left) shows a sewer line cleanout under and building exit piping under construction at a New York Home. The image illustrates a new plumbing drain cleanout access port being installed in a home.

The in-building drains (not visible here) were 4-inch ABS pipe. The exterior sewer connection pipe was six-inch pipe. Photo courtesy Galow Homes.

When installing the plumbing drain cleanout the plumber continued the six-inch piping up into the building through the drain cleanout fitting, providing an easier-to-use wider drain cleanout opening.

The extra cost of continuing 6-inch piping up to this location was trivial and makes drain servicing much easier. At the left side of the photo the drain piping is adapted down to the 4-inch in-building drain size.

Because of the larger diameter cleanout TEE installed in this case, the plumber installed a 90 degree cleanout tee. In most of our other plumbing cleanout port photographs you'll see that the cleanout access is installed with an angled fitting to assist the plumber in routing a plumbing snake in the direction most likely to be needed to clear a slow or blocked plumbing drain.

Plumbing chase covered with fire-rated Drywall (C) D Friedman

Because this plumbing drain exit point was located in the home's garage, local building codes required that we enclose the plastic piping in a chase covered with fire-rated drywall.

Even before the fire barrier drywall, the inspector also required that we use fire-block foam insulation to seal the pipe penetrations in walls, ceilings, and floors.

And because the fire-block foam could not itself be left exposed, where that material was used at other penetrations through the fire-rated drywall, those penetrations were sealed with fire-caulk.

Finally, the builder (Galow Homes) provided a metal plumbing access cover so that it would still be possible to access the plumbing cleanout if necessary.

Outdoor Cleanout Port for Sewer or Septic Line Piping

Plumbing cleanout (C) D Friedman

Often an outdoor cleanout is provided to permit snaking and clearing the building sewer line connection (circled area in photo at left). In this home which is slab-on-grade construction, there was no indoor provision for a building drain cleanout access in this wing of the home; the builder constructed this plumbing cleanout access just outside of a bathroom wall. Photo courtesy Galow Homes.

Building Plumbing Drain Cleanout Problems & Defects

Plumbing cleanout (C) D Friedman

Using the building drain cleanout to add a washing machine or sump pump drain connection is an overwhelming temptation because of the convenience (photo at left) but this installation gave no thought to the future need to inspect or clear a blocked drain line.

The result will be extra trouble and cost when drain de-clogging is needed.

Plumbing cleanout (C) D Friedman

When the finished building wall in this basement was removed as part of a mold remediation project we discovered that a house trap was leaky - it has been replaced in this photograph.

And because the original house trap and cleanout access had been buried behind a finished wall the cleanout was not readily accessible, nor was its location even known to the current homeowner.

Our two building drain cleanout access photos (below) illustrate a surprisingly common and both dangerous and unsanitary condition: the building drain cleanout is left open, risking entry of sewage and sewer gases into the building.

Plumbing cleanout (C) D Friedman Plumbing cleanout (C) D Friedman

At below left our photo illustrates a connection of copper drain to the cast iron building drain in a basement. You will notice that the copper drain line (circled at upper left) includes a cleanout access port.

Plumbing cleanout (C) D Friedman

Unfortunately the copper connection in the lower right of the photograph (arrow) is improper, unreliable, and perhaps unsanitary.

Reader Question: what types of plumbing cleanouts are used in homes & does greywater flow into the sewer line?

1 March 2014 Debs said:

My house is over 40 years old and we had roots growing into the sewer line. Plumber could not locate the sewer cleanout (he went under the house and around the house and we only could locate one cleanout, which was next to the kitchen.) so he installed one which of course is connected to the sewer pipe which is fine.

My neighbor stated there was no reason to do this since all grey water goes thru the sewer line. Can you explain to me what types of cleanouts are used in homes? Also, does the grey water from the kitchen flow into the sewer line as well?

Sewer line cleanout, Surprise Arizona (C) Daniel FriedmanReply: locations & uses of plumbing drain cleanouts

Debs I cannot make sense whatsoever out of your neighbor's comment that drain cleanouts are unnecessary.

[Click to enlarge any image]

What is a plumbing drain cleanout and what's it for?

A plumbing drain is an opening in a drain line, typically a Wye, that is covered with a removable cap to permit drain cleaning or un-clogging.

Drains serving both blackwater (toilets) and graywater (laundry, dishwasher, kitchen sink) can clog. Building plumbing drain lines can clog for a variety of reasons such as poor slope, accumulation of solids, root invasion, items flushed down toilets, corrosion in galvanized iron, soap sludge and scum, and other blocking materials.


The plumbing drain cleanout gives access to various drain sections to permit use of an auger or drain cleaning tool. Both hand operated and power-operated drain cleaning tools are used as well as other drain cleaning methods (compressed air, chemicals, and even drain line replacement). .

Where are plumbing drains located?

Typically there is at least one main drain cleanout where a sewer line leaves a building - the main drain cleanout.

In the photo guide above, at A Photo Guide to Plumbing Cleanouts & Cleanout Problems you can see a main cleanout installed where a building drain leaves the structure. Outdoors there may be additional drain line access covers to extend the reach of drain cleaning tools.

A thoughtful builder (or plumbing inspector) may install (or require the installation of) drain cleanouts at areas that woudl be hard to access or get past during a building drain cleaning operation from a sink or toilet.

Additional drain line cleanouts, if present, may be located in various locations based on convenience and need. For example where there is a long drain run cleanouts maybe installed at intervals - since handling a very long plumbing snake or drain auger is more difficult than using a shorter one.

Plumbing drain cleanouts are also installed at changes of direction and of course in different sections of drain lines before intersections.

Other access points may be used to try to clear a drain where there is no cleanout, such as by

Where greywater flows in a building depends on its drain design. In most buildings the greywater joins blackwater enroute to a public sewer or privat septic system. At properties where septic drainfield capacity is limited or there has been a history of failures, often graywater is routed to a separate drywell to reduce the load on the septic system.

Other reasons that grey water may be routed to a separate drain system include:

Convenience: if a kitchen or laundry are located where connecting their drain to the main building drain line is difficult or costly on occasion we see the contractor or plumber install a local drywall close to the point of use of those fixtures.

See GREYWATER SYSTEMS for more about graywater systems.


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