Reuben's Home Inspection Blog


Moldy Shower Caulk... Fixed!

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.

Reuben Saltzman, Structure Tech Home Inspections


Comment balloon 85 commentsReuben Saltzman • April 19 2011 06:25AM


There are several "mold and mildew" removers on the market that works really well. I have used "off the shelf" products and they are good. Did you look in the local Home Improvement store first?


Posted by Clint Mckie, Desert Sun Home, Comm. Inspection 1-575-706-5586 (Desert Sun Home, commercial Inspections) over 8 years ago

Brilliant! I am going to try that!

Posted by Dennis Swartz, MBA, GRI...experience counts! (Full Circle Property Management) over 8 years ago

This is a great tip! I hate removing caulk so anything that can be done to prevent that is good!

Posted by Renée Montgomery, Northern Virginia Real Estate (Century 21 New Millennium) over 8 years ago

Clint - no, I haven't tried any of the off-the-shelf mold removers, and I didn't even check out what my local improvement store had to offer.  I'll have to do that.

Dennis - just watch out for those fumes.

Renee - I hate removing caulk too.  I'm glad I didn't have to do it.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 8 years ago

Wow, what a difference.   I will need to keep this on hand for some of my customers who have this issue.

Posted by Debbie Gartner, The Flooring Girl & Blog Stylist -Dynamo Marketers (The Flooring Girl) over 8 years ago

Great tip, I have to try that myself. Thanks!

Posted by David Karp, Woodstock, Marietta GA Real Estate (Peachtree Realty Group, LLC) over 8 years ago

Very impressive Reuben. How is the caulk affected by the whole process? It's definitely whiter but has the viscosity been changed? It could be more brittle, but could also be better, meaning improved flexibility.

Either way it's a great clean up job.

Posted by Robert Butler, Montreal Home Inspector | Aspect Inspection (Aspect Inspection) over 8 years ago

Debbie - I'm sure you've seen your share of nasty showers... maybe not as bad as mine though :)

David - It's pretty easy.

Robert - I'm not sure what the bleach did to the caulk, although I'm guessing it probably didn't help it much.  Even if it shortens the life expectancy, it was better than removing it all :)

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 8 years ago

Agreed, I'm going to re-blog. Homeowners will find this of good practical use. Thanks.

Posted by Robert Butler, Montreal Home Inspector | Aspect Inspection (Aspect Inspection) over 8 years ago

Great tip. I'm going to pass this along to my customers in my newsletter, with your permission.

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 8 years ago

Thanks Robert.

James - Thanks, and yes, of course you can use this.  For the record, you have my permission to re-use any of my stuff any time you want :)

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) about 8 years ago

Hi Reuben - Those are some amazing results! I'll definitely keep this in my "tips & techniques" toolkit, as my clients may be in need of some help in this area. Thanks!

Posted by Judy Klem, Home Staging, Senior Move Management, Fairfield/New Haven counties (Transition Stage LLC) about 8 years ago

Hi Reuben - Great results! Bleach is horrible to work with though, as you have said.  I wonder if vinegar and baking soda would have any good results--I might just have to try it.

Posted by Peggy Chirico, REALTOR® 860-748-8900, Hartford & Tolland County Real Estate (Prudential CT Realty) about 8 years ago

Reuben, cool!  We've done a lot of jobs where we ended up removing the caulk, cleaning the cracks, and re-caulking.  That method is VERY labor intensive.

Was the caulk a latex base or silicone base?  Or could you tell?

And I especially like the new shiny corner, even with the little "twinkle" that shows it's really clean.  I can even hear the sound of the shiny star twinkle in my head looking at your clean shower caulk.

Posted by Jeremy Wrenn, C.O.O., Winslow Homes (Winslow Homes) about 8 years ago
Great idea. My sister always keeps a spray bottle filled with bleach and diluted water which she sprays after showering and that has kept the mould away. Keep away from the children though!!
Posted by Patricia Clough over 5 years ago

Those results are amazing!  Simple and inexpensive but a powerful difference.  I had never heard or thought of covering with the plastic wrap (or letting it set so long).  

Posted by Karen Mathers - REALTOR®, When it Matters, Choose Mathers! 772-532-3221 (Keller Williams Vero Beach) over 5 years ago

The results look amazing! I had never heard of something like this but definite some very usefuel information.

Have a blessed day!

Posted by IRMA Beltran, Your Real Estate Agent 4 Life Always there 4 You! (Century 21 M & M and Associates-Turlock homes Real Estate) over 5 years ago

There are so many places in homes where unwanted sights and smells can occur.

Posted by Jeff Jensen (The Federal Savings Bank/Lending in 50 states) over 5 years ago

There's a way easier way to do this:

Mix the baking soda and bleach in a gallon size plastic bag. Seal it up and massage it to mix the baking soda and bleach. Snip off a little corner of the bag (no matter how much you think you need, do half of that!) Squeeze it into place. Let it sit about 8 hours then wash off with water.

Fyi, use the rest of the solution on any grout. Scrub with a toothbrush after having it sit for 15 mins, then wipe off.

Posted by Anna almost 5 years ago

I just mix the bleach with baking soda in a bucket then apply copious amounts with cotton strips and apply the areas and leave on for an hour or so. The results are impressive. I don't understand why a mold resistant caulking hasn't been manufactured yet considering the need.

Posted by Maude over 4 years ago

Bleach does not kill just turns it white. Make a paste with borax and you kill it.

Posted by Rhonda about 4 years ago

Best caulk to use is exterior caulk. They have mold resistance caulk but its 100 silicone and only gives maybe a 7 year protection.

Posted by Kim about 4 years ago

Liquid Drano also does the trick.

Posted by E almost 4 years ago

Great idea

Posted by Susan almost 4 years ago

Do you think this would work on tile grouting?

Posted by Dick Adams almost 4 years ago

My boyfriends tub was actually worse than the picture. So I used this recipe. Except I put on plastic gloves and spread the mixture on by hand. And YES IT TRUELY DOES WORK!! THE TUB LOOKS LIKE NEW AGAIN!!

Posted by Tina McKnight almost 4 years ago

Yes I have tried a version of this before, Any tips for removing rust stains form toilet bowls. Have tried similar mixtures and various commercial preparation without satisfaction.

Posted by margarette almost 4 years ago

I don't understand about the plastic wrap. so after I apply the Cleaning paste on the bath tub I cover it with plastic wrap? how can I do that on the corner walls? do u have a photo or video to share.

Posted by Elen almost 4 years ago

Try lime I. Toilet. Let stand a few hours use toilet brush or scrubber/gloves. Flush. Repeat if necessary.

Posted by izzy moe almost 4 years ago

Is this bleach solution safe to use on a colored tub with colored tile bordering it (the caulking is white, well moldy black for now, but supposed to be white!)? Thanks

Posted by A almost 4 years ago

Go to Sallys and purchase a color brush like $2, and the bristles won't melt.

Posted by swayves almost 4 years ago

You didn't kill the mold.... you just bleached it. It will regrow.

Posted by Robbie almost 4 years ago

Sounds great, but vinegar, and baking soda may be healthier to your lungs. I can't get a respirator.

Posted by Brook watson almost 4 years ago

Bleach kills mold

Posted by Nicol almost 4 years ago

Does anyone know if leaving the bleach mixture that long will discolor a colored tub/tiles?
Thank you

Posted by A almost 4 years ago

Bleach it's great for cleaning mold. I never had any discoloration issues on my tile at all, or grout. I have used a bleach gel pen on my grout, that works great too, would probably work on the caulk as well now that I'm thinking about it.

Posted by Lindsay almost 4 years ago

Information of chlorine bleach and mold

Posted by iamvixie almost 4 years ago

Bleach should never be mixed with other chemicals or poisonous fumes will result. I don't advise this mixture.

Posted by Valarie Stewart, Scientist almost 4 years ago

I put bleach in a spray bottle and spray the mold.

Posted by DR almost 4 years ago

I found an easy way. Buy some cotton roll that you use for hair permanents soak in bleach thenPut around on moldy caulk stuff it up against it and let set. Remove if some mold is left in places return cotton to that area let set more.

Posted by Joanne almost 4 years ago

i found that vinger,baking soda, and blue dawn mixed into a paist work great! Less fumes then bleach

Posted by carletta almost 4 years ago

Baking soda and bleach mixed together releases chlorine gas. In an enclosed space this can kill you! A respirator to clean your caulk? That sounds like few people would do this, and you need to get other folks out of the house....animals too. Kind of like huffing oven cleaner, I just don't suggest it.

Posted by Barbara Hill over 3 years ago

Barbara Hill, it is bleach and ammonia that is dangerous not baking soda.

Posted by Cheryl over 3 years ago

Great idea I'm gonna try this today!

Posted by Maggie over 3 years ago

So is just bleach and baking soda. ..mixed together....

Posted by gerta over 3 years ago

I use Zep from the big box store, not very expensive and very effective. I'm sure it contains bleach also because you can surely smell it. Just spray the pink or black mold, let sit for 10-15 min and its gone no brushing,no touching just rinse .....

Posted by Dave over 3 years ago

I've been using it for yrs. But never heard about the plastic wrap. Great idea 💡!

Posted by Jo over 3 years ago

فكرة ممتازه سوف اجربها أشكرك

Posted by ريحانه over 3 years ago

Jo so basically you don't need to use the plastic wrap?

Posted by Nikay over 3 years ago

This didn't work for me whatsoever.

Posted by Senga over 3 years ago

You really do not need the baking soda only for a paste if you want!Dianna

Posted by Dianna Dettrrman over 3 years ago

If this did not work for you, you better rip out the caulk and put in new or get a different house!

Posted by Dianna over 3 years ago

In spanish. Or. French? Please

Posted by Maru over 3 years ago

Reading comments Im amazed how dumb ppl are.. especially the ones that think theyre a scientist. Mixing bleach and baking soda is not harmful. Its about as harmful as using straight bleach. All youre doing is making it into a paste.

Posted by Nicklaus Michael over 3 years ago

Go to Sally's beauty supply and buy the long rolled 1/2 tube-shaped cotton t5hat is wrapped around your hairline when getting a perm or color in a salon. lay the cotton in place around the tub and then use a dye applicator bottle with the small open tip to pour a thin flow of straight bleach onto the cotton. Use an old wooden spoon or paint stirring stick to push the saturated cotton up against the mold. This is faster & you are exposed to the bleach for a much shorter period of time. turn the fan on and close the door as you leave the room. Still wear a mask while pouring the bleach onto the cotton. Start at the furthest point & work your way towards the door.

Posted by Janie over 3 years ago

Fill a spray bottle w bleach or just water and keep the mixture wet to keep it from drying out. If use bleach label the spray bottle as bleach don't mix any other chemical w the bleach. It can cause a gas.

Posted by Jean fradenburg over 3 years ago

I'll have to try this one out !!!!!

Posted by Katie over 3 years ago

This is just what we need!

Posted by Steve Braun over 3 years ago

Hi ,I miss understand I put the plastic rape over the solution on the mold.can you please guid me I want to try.thanks

Posted by Therese over 3 years ago

Please if you have pets remember keep an exhaust fan on or a window slightly open and keep them in a separate room or floor of your house. I think Janie gave the best tip it's easy, less of a mess and plastic will slip when it's in contact with water.

Posted by Cyndy over 3 years ago

Once clean, if you spray the grout area at least once a week with a 1/2 bleach 1/2 water spray, leave on and rinse later, you won't have this problem.

Posted by Lea over 3 years ago

and please remember that bleach and citrus / acid or lime scale chemicals will make a gas that will kill you. So if you have used lime scale remover in the shower or sink earlier then dont use bleach BEFORE you have washed the area with water.

Posted by Rene over 3 years ago

What if your grout is colored?

Posted by Molly over 3 years ago

Can you use this on a tile shower? Thanks

Posted by JenD over 3 years ago

Spray vinegar on the mold. Works fine on all colours without this palaver. I use cleaning vinegar which is 3 X stronger than table white vinegar. I buy it in Lidl 89cents a litre

Posted by Lyn over 3 years ago

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

Posted by Jace Janiero over 3 years ago

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

Posted by Brenda kirby over 3 years ago

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

Posted by Amber over 3 years ago

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.

Posted by Michela over 3 years ago

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.

Posted by Fernando over 3 years ago

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

Posted by Sandi over 3 years ago

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

Posted by Nette over 3 years ago

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!

Posted by Carolyn Fimiani over 3 years ago

Vinegar also kills mold. Bleach can cause lung damage.

Posted by -- -- over 3 years ago

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.

Posted by MamaSmurf5000 over 3 years ago

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

Posted by trashtotreasure over 3 years ago

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!!

Posted by Amber S about 3 years ago

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

Posted by Sandra almost 3 years ago

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.

Posted by Cobbscout almost 3 years ago

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

Posted by Kelly over 2 years ago

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

Posted by Betty almost 2 years ago

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!!! 🤞🏻

Posted by Julie Smith almost 2 years ago

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

Posted by Lori over 1 year ago

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

Posted by Kathie Stevenson over 1 year ago

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!

Posted by Max Malavansky over 1 year ago