FAWs about how to protect building drains from freezing:

This article series explains how to prevent frozen drain piping and freeze-damage or burst drain pipes in buildings and in the building connection to a septic system or to a municipal sewer line.

Q&A on How to Avoid Frozen Drain Pipes

These questions and answers about ow to avoid freezing drain piping, drains, traps, toilets, etc. were posted originally at DRAIN FREEZE PROTECTION - you will be warmed and have fewere busted pipes after reviewing that advice,

On 2019-03-11 by (mod) - using heat cables on buried drain lines

There are heating cables that can be used in a buried drain line including plastic pipe, but a better repair would be to use solid wall PVC that doesn't have Hills and Valleys so that you're not dependent on electrical current to avoid Frozen burst pipes or water backups around your house

On 2019-03-11 by michel leblanc

My problem is freezing of an exterior plastic extendable pipe from my roofing downspout. the pipe is approx. 7 metres long extending away from the house foundation.

The water does not flow perfectly (gravity) within the pipe because the ground it lies on has some highs and lows. Standing water within the pipe freezes and eventually becomes blocked with ice. Is there a cable that can be put in this plastic pipe to prevent freezing.

On 2018-01-18 by (mod) - drips or running toilets freeze in drain line

Paula

Usually when I find this problem it's because dripping faucets or a running toilet are sending a SLOW rate of water into the building drain system. Normally even a drain that is exposed to freezing temperatures won't freeze up solid when wastewater flows through it to a septic tank or to a public sewer.

But slow trickles of water passing through a very cold drain line can indeed build-up ice and freeze until ultimately the line is blocked.

So I would start by looking for drips and running toilets.

See TOILET REPAIR GUIDE

On 2018-01-18 by Paula

Every time we have a hard freeze, which hasbeen happening nightly, but is actually rare in my part of the country, bath tub, sink, and toilet back up and are full of wayer that doesn’t drain until the weather warms above freezing for several hours. Then it idrains until it is below freezing again then backs up.

Does ice form in our drainage pipes?? How do we prevent that or stop it from happening? We let warm water drip allday & night already.

On 2018-01-05 by (mod) - how to thaw inaccessible frozen drains

Mike,

Sometimes when a frozen pipe is inaccessible, plumbers use a combination of flexible tubing, a bucket of hot water over a burner or heater, and a pony pump to circulate hot water through a otherwise inaccessible pipe to the area of ice blockage.

On 2018-01-04 by Mike

I have a 2 inch lateral on a raised River cabin it is enclosed with insulation but the lateral pipe from the kitchen to the stack 15 ft away is clogged how do I breakthrough any ice frozen into in lateral it's a vertical drop to a 90 ...15 feet of pipe to the 4in stack

On 2018-01-02 by Terry

I think my pipe leading to my septic is frozen. Its been -12° here. I bought a heater to put in my crawl space where my pipes are. Shd i place it in my downstairs bath? Or crawl space. My tub isnt draining?

On 2017-12-27 by (mod) - where & how add heat to avoid frozen drain line

April

Insulation slows heat loss but it also prevents heat gain when temperatures around a pipe warm up (as weather changes). So the benefits can be mixed.

A PVC drain pipe, along the route of a drain, should never freeze, even when exposed to low temperatures, because the drain is not holding water - unless the drain is blocked and thus draining slowly (or perhaps a toilet runs sending water slowly into the drain, permitting it to freeze-up).

But a trap below a shower hanging down into a cold crawl area might freeze. If you're already warming the garage then a neat trick is to cut an opening in the ceiling below the trap, thus letting warm air from the garage to enter the floor in that area.

See HEAT SOURCES to AVOID FROZEN PIPES for an example of areas where we've added heat to avoid this problem

On 2017-12-27 by April - freezing shower drain

I have a shower drain that freezes every year. No other drains in the house freeze.

The water to this shower has frozen in the past but the drain is the first to freeze. I have added insulation to the water pipes and that has kept them from freezing again. Is there a insulation that is recommended for PVC drain pipes? What other options do I have for the shower drain?

The shower is above a unheated garage. I keep a radiant heater running in the garage but to no avail.

On 2017-12-17 by (mod) -

Dawn

Where I've had the problem you describe I found a way to get heat to the area of the waste pipe to avoid freezing, in some cases simply making an opening from the heated space.

But that is only a "band-aid" repair. The root problem is usually that your waste line is clogged. It's the clogging that leads to standing wastewater in the pipe that permits freexzing. An un-clogged waste line usually will drain fast enough that it won't freeze.

An exception: even an un-clogged waste line will build up ice and freeze if there is a slow but constant trickle of wastewater into the drain, for example from a running toilet.

On 2017-12-12 by Dawn

Main waste pipe has frozen nd bathroom floor flooded. What can I do I live alone

On 2017-08-23 by (mod) -

Bill:

I don't quite follow the depth question; the drain needs to slope 1/8 to 1/4" per foot to its destination to drain properly; in turn that means that the drain ought not freeze as it won't be holding water.

I can't guess at the disposal solution since we know nothing about your site, but you might look into a drywell.

On 2017-08-17 by Bill

I live in PA. Planning on putting a drain in my new garage floor wanted to know what kind of depth ,and also if I plan on using a stone drain field for the discharge.

On 2016-09-07 by Debbie

How can I keep drain pipes and traps from freezing in an Unheated crawl space? My house doesn't have a foundation; it's up on blocks- but the area will be closed up. I Live in upstate NY.

Reader Comments:

(Feb 18, 2012) Isaac said:

This is really great information. Thanks to whoever took the time to write these articles.

Reply:

Thanks Issac, we work hard to make InspectAPedia content real, authoritative, and useful.

So while a compliment is wonderful, (and keeps me going) if you find something is missing, confusing, or inadequate, you're doing us a favor to ask for more information.

...

Continue reading  at DRAIN FREEZE PROTECTION or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Pipe Freeze Protection Articles

• ANTIFREEZE for BOILERS
• DRAIN a WATER HEATER TANK
• FAUCETS, OUTDOOR HOSE BIBBS
• FREEZING FORCE of ICE
• FROZEN PIPE THAW-OUT
• GREYWATER FREEZE PROTECTION
• PIPE FREEZE PROTECTION - home
  • DRAIN FREEZE PROTECTION
  • HEAT SOURCES to AVOID FROZEN PIPES
  • HEAT TAPES to AVOID FROZEN PIPES
  • HEAT TAPES on OIL TANK PIPING
  • HEAT TAPE HAZARD ON OIL TANK
  • INSULATION to AVOID FROZEN PIPES
  • PIPE FREEZE-BURST PATTERNS
  • PIPE FREEZE-UP POINTS
  • PIPE FREEZE PROTECTION CABLE ASSEMBLY
  • PIPE INSULATION CHOICES, MATERIALS, TYPES
  • WELL SNIFTER & DRAIN BACK VALVES
• WINTERIZE A BUILDING - home

Suggested citation for this web page

DRAIN FREEZE PROTECTION FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING FREEZE PROTECTION

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