Peeing with a drysuit
Being cold and underwater increases urine production (see Learn More below if you want to know why). As a result - there is a saying that there are only two types of divers - those who pee in their wetsuit and those who lie about it!
But what about drysuit divers?!
Peeing in your suit is not a good option. So as a drysuit diver you can try to pee right before a dive and hope you can hold it, or avoid liquids before diving (this is not a good idea because it can lead to dehydration which impedes body function and dehydration increases your decompression sickness risk) or, you can install a pee valve!
The rest of this article is all about pee valves - written as I'm trying one out for the first time. If you find that you are cutting your dives short to get out and pee or you have been dehydrating yourself so as to not wet your drysuit - this article is for you!
Equipment You Will Need
A urine collector. This connects to your anatomy to collect your pee. Men use external catheters (also called condom catheters or uridomes) and they look and function more or less like a regular condom - but with an opening at the tip for urine to escape. For women the collector is a silicone cup with a flange to make a seal. In both cases, the collector is held in place with medical glue. Urine collectors have a short tube built into them to let the urine pass out. This outlet connects to a tube fitting
A tube fitting. This connects to your urine collector on one side and to your tubing on the other. Opting for a quick-disconnect style fitting makes it easy to clip in and out of your pee valve when donning and doffing your drysuit. As a diver you're already familiar with one type of QD fitting. Quick disconnects are used on BCD and drysuit inflator connections!
Flexible rubber tubing. When standing, the top of this tubing connects to the tube fitting that connects to your urine collector. She-P outlet valves point towards your head. Male external catheters can be pointed either toward your head or toward your toes - your choice. If you opt to point your urine collector with the outlet toward your head, the tubing will need to be routed in a gentle 180 degree turn to head back toward your toes. Don't bend the tubing tightly as it could kink, blocking flow. From there, the tubing travels down the inside of your drysuit undergarment leg (left or right is your choice). Its far end emerges mid-thigh through a hole in your undergarment (many come pre-cut with slits for this purpose). There it attaches to a male tube fitting to deliver the uring to your pee valve.
A pee valve. The valve is typically installed mid-thigh and mid-way between the front and inner thigh. This minimize interference with kicking (which would occur if you installed on your inner thing) and snagging on things (which would be more likely if you installed on the front of your thigh). The pee-valve allows urine to pass out into the water when you are diving. It works just like your shoulder exhaust/dump valve - except it passes liquid instead of gas.
Example Equipment List
Urine collection equipment
Men: Hollister InView™ silicone external catheter https://medicalmonks.com/product/inview-male-external-catheter-standard-fit/ .
Women: She-P https://www.she-p.com/
Quick disconnect tube fittings
urine collector-to-QD fitting: https://www.diverightinscuba.com/p-valve-quick-disconnect-male-end-to-catheter.html You may want to have extras of these. You can use them to connect equipment that you use to rinse your p-valve. They are also handy if you drop or misplace a fitting in the process of donning and doffing your urine collector.
QD assembly: This includes two pieces, the fitting above as well as a fitting which connects to the urine tube and stays in your drysuit. Because it stays attached to the tube in your drysuit where you can't lose it - you should only need one. https://www.diverightinscuba.com/drysuitsundiesaccessories-lightmonkey-quickdisconnectforpvalve-p-3110.html
Si-Tech TRIGON pee-valve with hose. https://www.sitech.se/products/dumppee-valves/trigon-pee-valve.aspx
The Process
Guys need to figure out which catheter size provides the best fit. Catheters are sized by diameter in millimeters (mm) - and sometimes by length as well. To estimate the appropriate diameter, start by measuring the circumference around the widest part of your anatomy at rest. You can use a cloth measuring tape of the type used for taking tailoring measurements. Or, if you don't have a cloth tape, use a strip of paper, mark the size, then lay the strip of paper out and measure the marked length with a ruler or tape measure. Divide your circumference in millimeters by pi (~3.14) to obtain your diameter. That should match the catheter size that will fit you. They are sold in sizes ranging from about 25 mm to 40 mm. You can order 1 each of a few sizes of the silicone Hollister brand catheters from the Medical Monks website above and try them on to verify sizing. You want it to fit snugly without excess diameter causing wrinkling or increasing the chances that it comes off. At the same time, it should not be so snug as to be uncomfortable or restrictive.
When donning your catheter take care not to entrap hairs under the cathether as they will become entrapped in the glue and this will make it uncomfortable to remove. Some divers find shaving may aid in this process. I find that a bit of care makes shaving unnecessary.
You may prefer other brands or choose to use latex instead of silicone. Generally latex is stretchier than silicone, which may accomodate size changes more comfortably if you find that to be an issue. You can also choose to order catheters with more glue (if you find that your catheters are falling off while diving) or in different lengths for a better fit. Male external catheters are used for urinary incontinence - so the market is fairly large and you have many choices.
Women using the She-P don't need to pick a size, it is one-size fits all product. The She-P website and a Facebook group have instructions for how to secure it in place. It attaches with glue as well, but the process is a bit more complicated than for guys. Also note that the She-P is re-usable whereas male external catheters are disposable, single-use items.
Order all your equipment including catheters. When it arrives have your local dive shop install the valve for you. You could attempt to install it yourself - but going wrong could ruin your suit.
Before you try your pee-valve on a dive, it's a good idea to give it a try at home where you can solve any problems more easily. Put on ALL your equipment (include your drysuit undergament to - to verify hose routing function) and give it a go! A shower is a good place to test it out. Once you've made sure everything works you are ready for a dive. Enjoy the freedom of not having to cut your dive short to go to the bathroom!
When your dive is over, drain your assembly. Do this by squeezing any liquid from your urine collector down into the tubing and out the valve. Then disconnect the QD tube fitting. You can wait until you get home to remove your urine collector and its attached QD fitting . If you have to pee again before you get home, you can just pee through the equipment - so there is no rush to remove it. Also, the longer you wear your urine collector, the easier the glue becomes to remove.
After disconnecting yourself from the tubing if you use a quick disconnect fitting the remaining urine will be trapped in the hose because the check valve closes when the male half of the QD fitting is removed. To release this urine, grasp the tubing, hold the open end up (so it is the highest point in the tubing which ensures urine goes out your valve and not out the tube into your suit) and insert a spare male QD fitting into the female one. This will open the check valve in the QD fitting allowing the remaining urine to drain out your P-valve.
Finish by rinsing your P-valve with water. A sqeeze bottle with a tip sized to fit inside your QD fitting works nicely. It may be easier to rinse your tubing and valve while you are still wearing the suit. Some users recommend rinsing with vinegar first as a cleaning and deodorizing agent followed by water to remove the vinegar (which might damage some valve components if not rinsesd out). Check your manufacturer literature for the best cleaning method for your equipment - if in doubt just use water.
Once home, go ahead and remove your urine collector. It may come off with gentle tugging - if not - soap and water in a shower may help. Medical adhesive removers are another option to help release the glue.
COMMON PROBLEMS TO AVOID
kinked hose - this will prevent you from being able to urinate and can be very uncofortable. Check that everything works with a quick test on land or the surface before you submerge
kinked catheter tip - same result as kinked hose - this could block urination. Avoid excess length at the catheter tip by applying it properly. Guys - ensure the catheter outlet is aligned with your urethra (not off to one side where urine flow could be blocked).
quick-disconnect valve not fully connected - this can also block urine flow. Fix by completely plugging the two pieces together
LEARN MORE
The P-Valve Struggle from an SDI / TDI blog post - a good read, lots of detail - written from a male perspective.
She-P FAQs from the manufacturer.
Immersion Diuresis this article from Divers Alert Network (DAN) explains why scuba diving induces the urge to pee.