PottyPotty - the potty that cleans your potty

Update: I've added a second version with a thinner tank/trap section. It seemed like version 1 dispensed a little too much per flush and only lasted about a month. 

After months of pondering, I finally cracked the code on a passive device that meters out a small dose of cheap powdered cleaner into the tank with every flush. No saturated cleaning solutions attacking your toilet parts, no expensive tablets that only last a month, no rigging something up to the water lines. Fill it with cleaner, drop it in the tank, and forget about it until the bowl stops being clean. 

Would you believe me if I told you the resemblance to a toilet is entirely accidental? I didn't notice until I was done designing it. But I will certainly lean into it.

How it Works

I am quite proud of the theory of operation. The “bowl” portion of the PottyPotty is filled with a cheap powdered cleaner of your choice. The main culprit at our house is rust stains, so I'm using bulk Iron Out powder. For general hard water stains, citric acid would be a great option. In the photo, I added food dye for demonstration.

The “bowl” is connected to the “trap” portion by a wall with angled holes. This section is like the trap of a drain, with a low u-shaped bend. the angled holes prevent the solid powder from flowing through to the trap, but allows fluid flow between the two sections.

when placed in the water, the powder begins dissolving. The powder remains in the bowl, but the dissolved cleaner solution flows through the holes into the trap. Being denser than the surrounding water, the cleaner solution is “trapped” in the low u-bend, and once the solution is saturated, no more cleaning powder can be dissolved.

When the toilet is flushed, the water level begins to drop. At this point, the water level in the “tank” or “chimney” section also begins to drop. This water has nowhere to go except through the trap section and out the side vents, pushing the saturated cleaner solution up and out into the tank. As you can see in the video, there is no blue dye in the water prior to flushing, but upon flushing, the dye is ejected from the trap. (Sorry about the stained toilet tank, but… if it wasn't stained, we wouldn't need this.)

As the toilet refills, the trap and tank refill. With fresh water back in the trap, new cleaning solution can dissolve, repeating the cycle. Only the amount of cleaner that can dissolve into the trap is dispensed every flush, so the cleaner isn't wasted, and should last a while. Version 1 for me lasted about a month, and I'm currently testing version 2, which should dispense less per flush - V1 seemed a little aggressive.

Printing

Prints with no supports. I printed in PETG, but may upgrade to ASA if the plastic begins to break down. Check chemical compatibility with whatever cleaner you plan to use.

PETG is denser than water, which should help it sink. If you have trouble getting it to stay under, you could put a rock or stainless nuts/bolts in the bowl section to weigh it down.