Activated Charcoal Filtration System for Tiny House Portable Urinal

Introduction: Activated Charcoal Filtration System for Tiny House Portable Urinal

Sometimes for off-grid living situations without access to septic or running water you need a stop-gap solution for human waste. It's beneficial to divert urine (urea) from solids in composting applications. This tutorial will show you how to create an odor-free portable urinal that actually filters urine using activated charcoal. Activated charcoal is used to control odor and also in water filtration applications (think Brita). It will store up to 5 gallons at a time. When you are done you can add it to your flower bed as a nitrogen rich fertilizer. All the materials were obtained for free, and about $5 worth of activated charcoal was used in the application. Let's get started!


You will need:

(2) 5 gallon containers (I used ones with 3" screw on caps I got for free from a restaurant

(1) empty milk jug

3-5 gallons worth of activated charcoal.

a drill or a thin nail and hammer

Step 1: Drill Filtration Holes in Charcoal Storage Unit

Using a drill or a thin nail and hammer, make a series of 10 holes or so in less than a 2" diameter circle or square on the underside of one of the 5 gallon containers. You will want to drill the holes on the bottom directly under the spout. You want the holes to be smaller than the pieces of charcoal (a 1/8" bit will do).

Step 2: Fill the 5 Gallon Container With Activated Charcoal

You can purchase activated charcoal bulk online. Fill the 5 gallon container through the 3" spout. You can fill it all the way, or 2/3rds, or whatever you want. This container will sit on top of the collection container. These particular containers stack nicely.

Step 3: Stack the Charcoal Filter Container on Top of the Collection Container

I used the top 2" cut off of a 16oz water bottle to act as a filter, but you don't really need it, as long as the holes are directly over the spout of the collection container.

Step 4: Make the Urinal

Once the filtration container is stacked, get a 1 gallon empty milk jug (opaque is best) and cut off the bottom 1" from the bottom. Then cut out along the lines in the picture. Place the upside down cut out milk container in the 3" spout on filtration container. You may need a piece of 1/4" foam or some thick duct tape to keep it secure.

Step 5: Pee!

The stacked height is the perfect size for most men (I am 5'11") but if you are shorter you can use a small step stool if you want. The urine will filter through the activated charcoal, eliminating odor in the process, and collect in the bottom container. The filtered liquid urea may be blackish the first time due to the activated charcoal, but that happens in Brita filters as well, which is why you usually flush it 3-4 times before using. You're not drinking this stuff anyway, but after a few cycles it should come out clearer. Keep the cap next to the unit and when it's full, just haul it out to the garden or wherever. This also works well if you are on well water in the event of a power outage and aren't able to flush your toilets. When the container is full, you can use it to flush solids as well if you don't have running water in such a situation.

Hope this was helpful!

1 Person Made This Project!


  • Space Contest

    Space Contest
  • Retro Tech Challenge

    Retro Tech Challenge
  • Robots Contest

    Robots Contest



Question 1 year ago on Step 5

This is a great idea! So how often would you need to replace the charcoal say if you only used this a few times a week? Would the charcoal then have the really bad ammonia smell instead of the urine? I use a composting toilet on my houseboat and I don't like emptying the pee jar because of the smell. I may take your idea but just add a Brita filter into my set up as I don't have the space for another jug. Do you think this would work or is the mass quantity of charcoal necessary? BTW - Don't forget the ping pong ball trick. I love that it is the perfect odor stopper when placed into the funnel part of the urinal. It floats up when you pee and then settles back in to plug the hole once the urine has drained and prevents any smells from escaping. Or do you not have any odor escaping from the charcoal and so a ping pong ball would not be necessary?


Answer 1 year ago

I think the pinpong ball is a great idea! But I haven't had any issues with odor. At all. In fact, I've been using it for about 3 days now and it yes to filter all the way through the 4 or so gallons of activated charcoal to the collection container. I think the larger volume of activated carbon helps a lot. I really can't see myself emptying this thing more than once every few weeks.