Many of you are familiar with bath or shower bombs — those homemade (though you can buy them in the store too) concoctions of household ingredients that look like chalky golfballs and foam up when dropped in your tub. They smell really nice too!

Well, you can make holding tank bombs too and they do a great job of helping to keep your RV’s waste holding tanks clean. Based off of the GEO method of RV holding tank maintenance (basically, Calgon water softener and Borax laundry detergent, though sometimes baking soda and bleach — probably not a good idea), these pods do a great job of helping to keep your RV’s waste holding tanks clean between professional hydrojet cleanings.

Ingredients for the bombs

The ingredients are pretty simple: Borax, baking soda, citric acid and just a few drops of water. The first two can be found at most supermarkets and grocery stores; the citric acid may also be found there (try the baking aisle or the canning section), though you can find it on Amazon at a much better price.

Citric acid is a very mild acid found in lemons and limes and generally considered safe for your RV’s holding tank seals and other sensitive waste system components. It’s used in shampoos, facial peels, and body scrubs. It’s even used to clean aquariums — an environment where even trace amounts of chemicals can prove to be very detrimental to sensitive fish.

  • 1/3 c Borax
  • 1/3 c Baking Soda
  • 1/3 c Citric Acid
  • 1 tsp. Water

Instructions: Putting it all together

  1. Mix Borax, baking soda, and citric acid dry ingredients in a gallon size Ziploc bag. Mix well.
  2. Add several drops of water, to allow ingredients to bind together. Mix well. May need to add several more as you go.
  3. Pack tightly into silicone molds (we use the type that makes round, golf ball-sized ice cubes for cocktails). Let dry overnight.
  4. Pop out of molds. Let the bombs continue to dry for 1 to 2 more days.
  5. Store in airtight container until used.

The key here is to keep the water to a minimum: Use only a few drops at a time, enough to just get the ingredients to stick together. Anything more and it becomes a soupy mess (not to mention the bombs will expand out of the molds and, well, really make a mess).

How to use the bombs

After you’ve emptied your black holding tank (though these work well in your gray ones too!), put in a couple of gallons of water (a 3-gallon pail full of water dumped down the toilet is ideal here). Drop in a bomb and then let it do its work. For even better results, do this before you travel to your next RV park or site — the gentle sloshing action while you travel will help the bomb break down and the foamy soap to clean your RV’s holding tanks.