Moldy Shower Caulk... Fixed!

Home Inspector with Structure Tech Home Inspections

Dirty bathrooms are a huge turnoff for home buyers.  Mold is another huge turnoff.  Combine the two and the 'yuck' factor multiplies.  I think everyone has seen moldy bathroom caulk before, and if you've tried cleaning this stuff, you know it's impossible.

Moldy caulk in shower Moldy caulk in shower close-up

I recently moved in to home with some nasty looking caulk in the shower; that's my shower pictured above.  I figured I would need to remove all of the moldy caulking and re-caulk my shower walls to get them looking good again, but after doing some online research, I found a cleaning method that worked surprisingly well and wasn't much work.  Don't worry, I'm not going to turn this in to a Martha Stewart blog... but I was so happy with the results that I had to share the process.

Gather supplies. I grabbed a small mixing bowl, a jug of bleach, a box of baking soda, a disposable paint brush, a roll of plastic wrap, and a spray bottle.  The plastic wrap (orange handle, green plastic) shown in the photo below is the stuff you use to wrap things together, but you can also use the same plastic wrap you keep in your kitchen.  Oh, and one other thing - while it's not required for the project, I strongly suggest wearing a respirator.  Those bleach fumes are bad news.  Also, wear old clothes that you wouldn't mind spilling bleach on.  It might happen.

Cleaning Supplies

Mix up your cleaning solution. The cleaning solution consists of a bleach and baking soda paste.  You make it by mixing bleach and baking soda in a bowl until it's about the consistency of pancake batter.  The baking soda doesn't do any cleaning; it's just a cheap powder that will help make the bleach pasty.  Don't skimp on the cleaning solution here - go ahead and make way more than you think you'll need.  Bleach and baking soda are both inexpensive.

Disintegrated paint brush bristlesApply the cleaning solution to the moldy caulk. Use your disposable paint brush to apply the bleach paste on to the moldy caulk.  Again, don't skimp here; it's cheap, so cake it on.  I suggest you try to work somewhat quickly though.  The bleach is going to disintegrate the bristles on your disposable paint brush, so you don't have all day.

Cover the cleaning solution with plastic and wait. Covering the cleaning solution with plastic will help to keep the bleach from drying out.  Now you wait.  If you have a white porcelain kitchen sink or white porcelain whatever-else, spread the extra cleaning paste on it.  You can just let the paste sit for about 10 minutes, and then your sink will look brand new when you rinse the bleach off.  No scrubbing required.

Check on it. After the bleach has been sitting for several hours, it will probably have dried out, despite the plastic covering.  At this point, if the caulking looks as good as new, great!  You're done.  If you still have moldy caulk, put some bleach in a spray bottle and wet the walls down right above the plastic wrap.  The bleach will run down underneath the plastic and re-saturate the paste.  You can do this as many times as it takes, but even with my super-nasty caulk, I only needed to re-apply the bleach one time.

Now clean up.  At this point, your caulk should look brand new and bleachy fresh, or at least pretty close to it.  Now you can clean up the mess.  Water works just fine.  Click on the before and after photos below for a larger version to see how well this worked.  If I were a better photographer, all of the whites would have looked the same, but oh well... I think you get the point.

Moldy caulk before and after

Moldy caulk before and after closeup

I was amazed that this worked so well.  The entire project probably involved about 20 minutes of work, and required no elbow grease whatsoever.

And now, a word of caution:  do this project at your own risk.  Bleach is powerful stuff.  Read the warning label on the bleach.  It says to use in a well-ventilated area, don't let it touch your skin, don't breath the vapors, etc.  Bleach can also cause pits in metal.  I used it on the metal trim ring for my shower faucet and no pitting occured, but other people might not be so lucky.  Also, I'm not kidding about wearing a respirator.


Re-Blogged 3 times:

Re-Blogged By Re-Blogged At
  1. Robert Butler 04/20/2011 04:36 AM
  2. Judy Klem 04/26/2011 12:51 AM
  3. Chris Smith 06/07/2011 06:34 AM
Home Improvement
Ask the Home Inspector
Minnesota Real Estate Investor Group
Home Inspector's Corner
Minnesota Real Estate
WeBlog Anything (almost)!
moldy caulk
moldy shower caulk
moldy bath tub caulk
mold on caulk
how to clean caulk
how to clean moldy caulk
cleaning mo

Post a Comment
Spam prevention
Spam prevention
Show All Comments
Jace Janiero

Better read this before using bleach on grout. Grout is porous and even the Clorox people say not to use it on porous material

Jan 26, 2016 01:19 AM #66
Brenda kirby

Don't mix vinegar with bleach. A deadly combination.

Feb 01, 2016 08:43 PM #67

So your just bleaching the color out of the mold then, not actually getting rid of it!!

Feb 09, 2016 05:25 PM #68

The article says baking soda not vinegar. Amber.'re won't kill it. For that you will have to purchase an actual mold remediation chemical. Or strip the caulk, thoroughly clean the area, reapply the caulk.

Feb 09, 2016 11:46 PM #69

Bleach is an antiseptic and it will almost every microorganism exposed to it. Mold is a fungal type microorganism and it get killed by bleach easily. The bleaching effect is the chemical reactions between the chlorine and the color pigments. Of course it kill the mould but as you well know mold spores and bacteria are everywhere all the time and if you allow the right conditions (moist and heat)Mould will colonize the caulk again.

Feb 10, 2016 10:30 PM #70

Would this work on a front load washer?? The door boot has become mouldy from closing the door between usage.

Feb 12, 2016 12:21 PM #71

I just used that clingy toilet bowl cleaner on mine, and it worked like a charm.

Feb 20, 2016 04:14 AM #72
Carolyn Fimiani

I use Chlorox cleanup spray and it works much easier than this routine. I spray my tub-shower area every 2-3 days. Never get mold!

Mar 02, 2016 11:54 AM #73
-- --

Vinegar also kills mold. Bleach can cause lung damage.

Mar 08, 2016 05:35 PM #74

My daughter could not get the mild out of her mildew in her tub chalking and asked me for help. I tried but couldn't move it either as I saw it was not surface mold but inside it. I talked to my dad and he looked for the reason it existed. He pushed on one place on the shower wall and it moved. We ended up taking down the tile and found mold underneath. Fortunately the wood was still in okay shape. I cleaned up the lingering mold with bleach while they went to the store to purchase a tub surround. Please remember to look for a cause instead of just cleaning. That may just lead to it coming back again.

Mar 10, 2016 07:52 AM #75

An old toothbrush is also a great tool and the bristles remain in tact.

Mar 12, 2016 09:54 PM #76
Amber S

Instead of baking soda you can use borax which will keep the mold from coming back. This is a great cleaner and really does a great job at removing the mold and mildew!!

May 14, 2016 03:50 AM #77

This was a revelation absolutely fantastic!! 2 hours and whiter than new.. the easiest cleaning i have ever done. Thank you.

Jul 22, 2016 10:17 PM #78

WEAR GLOVES! Rubber, latex, or whatever but you should wear protective gloves when working with bleach.

I take paper towels and roll them individually into cigar shapes. Dampen them with bleach so that they stick to the caulk/tub/toilet/wherever. Then slowly drizzle more bleach until it starts to leak out. Tick tock. Bam! Clean.

Aug 04, 2016 11:56 AM #79

My tile is an ugly pink. Will the bleach mess that up if it gets on it? Thanks

Jan 04, 2017 09:31 AM #80

The ropes of cotton that hairdressers use for perms work great when pressed against the mold and sprayed with Clorox solution. It doesn't dry out as fast

Jul 26, 2017 07:53 PM #81
Julie Smith

Oh, I just finished reading on how to get rid of mold in my shower....I'm so excited to try this method! I've tried to remove all the old caulk with little success and applied a cleaning solution which had some bleach, but it still didn't come clean. I will give your idea a try and let you know how well it works! Sounds like a great time saver and a lot less frustration! Fingers crossed!!! 🤞🏻

Sep 06, 2017 07:14 PM #82

Be careful of leaving bleach on natural stone or marble for a long time. I am a professional housekeeper.

Oct 28, 2017 06:44 PM #83
Kathie Stevenson

When you are on septic bleach is a no no!!!

Nov 15, 2017 07:44 AM #84
Max Malavansky

Just spray with Clorox clean-up in a spray bottle every 3-4 days and you'll have no 👎problems with mold and mildew. Carol Fimiani has got it figured out too lol!

Feb 27, 2018 09:37 PM #85
Post a Comment
Spam prevention
Show All Comments

What's the reason you're reporting this blog entry?

Are you sure you want to report this blog entry as spam?


Reuben Saltzman

Delivering the Unbiased Truth.
Ask me a question
Spam prevention

Additional Information