Hairline crack on side of pool - no leak... yet


Nov 15, 2017
Los Angeles, CA

Today I noticed a hairline crack in the side of our pool. It's about 6 inches long on a ledge/seat on the wall at the deep end of the pool and extends down maybe 3 feet. It's very narrow, maybe 1/32" at the widest (at the top). Our pool is 50+ years old, and the plaster was last resurfaced about 15 years ago.

I did a little reading, and it seems the crack may be caused by loss of soil (pool is sort of at the top of a hill), or changing levels of moisture in our soil (dry in the summer, wet in the winter). I'm not sure how much I can do about either of these.

Even though there is no leak, is it a good idea to patch it now?

Is this something I, a reasonably handy pool-owner, can tackle?

If so, what should I use to patch it?

I appreciate the help.




  • hairline_crack.jpg
    289.6 KB · Views: 38


Mod Squad
LifeTime Supporter
Jul 10, 2012
Tallahassee, FL
For the shifting soil quite a few people in TX have a drip system around their houses and pool. This keep the ground moist during the dry time to keep it from shrinking.

I will call in someone who may know what to use to patch that crack @jimmythegreek

I will also suggestion to a "bucket test" to see if you are losing any water. A bucket test is where you use a 5 gal bucket and fill it up to a marked spot on the bucket and put it on one of the steps or such in the pool. That will show you if the pool is losing any water if the pool and bucket match at the end of the day or week. It is VERY important you turn off the autofill if you have one for this as that will hide any leaks.


TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
Morris Cnty NJ
Pretty easy to patch those. You can use pool putty, 2 part epoxy, 3m 5200, etc. Drain some water out so its dry and clean any gunk up then patch. There are some underwater potties avail. You could even open up the crack somewhat with a diamond wheel amd mix up a small batch of plain plaster and patch that way too


Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
Southern OK
3m 5200 will be there FOREVER , that stuff is crazzy... I have used the 4200 as sometimes you want to remove the part... :)


Gold Supporter
May 16, 2010
Chapel Hill, NC
I doubt you'll have any leaking through such a small crack. Drop some food dye on it and see if you get any movement into the crack.
Thread Status
Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.