The whole question of what to do when you need to "go" in the wilderness is a challenging one! There are many good solutions, depending on where you are, and indeed what you need to do. Accepted wisdom varies from using the inter-tidal zone, certainly for solid waste, to digging a trench on land and then backfilling afterwards. I pulled together some thoughts and suggestions in this article on "Coping in the Wilderness", but here's an interesting alternative.
The good folks at Karitek used to sell an American product called "Restop". Now, I've got some reservations about this, but it is certainly worth thinking about and could be a possible solution to a very real and increasing problem.
Essentially, the products allow you to safely and hygienically attend to your toilet needs in the outdoors and then remove the results for disposal when back in civilisation.
Restop 2 is a mylar bag which the makers say will allow you to capture solid waste, the whole process made easy as it has a wide plastic bag which funnels the deposit into the retaining bag. The whole lot is then pushed back into the bag and sealed.
Then, "super absorbent polymers and enzymes" and deodorizers turn the waste to a gel and the bag neatly stores the contents and "contains the odor as well as the waste, providing a user-friendly and pleasant means to pack out solid waste. Ample toilet paper and a moist antiseptic towlette are included." I'm not too sure about the pleasant bit, but it certainly works efficiently and is much better than many of the other "pack out" solutions I've heard about.
The makers also sell a commode which essentially turns the whole thing into a conventional toilet. I doubt it will go in a kayak though. Back in our world, the bag can be used without the commode, either by just squatting over it, or by building up a sort of seat using rocks.
Restop 1 is the same concept, but just for urine. Again, it turns the contents to gel, seals, and is disposed of "in the trash". I'm not too sure about the need for a disposable pee bag, but I suppose it could be helpful in some circumstances.
The makers make a big thing about this product being "landfill safe", but a little research tells me that the American definition of that is that the bag and contents won't break down and degrade. The up side of that is the prevention of methane gas production in landfill - the significant downside is that a quantity of mylar, plastic (hard and soft) is then being introduced to the landfill. And won't degrade.
Whether that outweighs the environmental impact of human waste being spread around our wild areas is another debate. Overall, in high use, sensitive areas, this product could well have positive benefits and if it were to help people in dealing with what is sometimes a challenging basic function in unfamiliar surroundings, then that's a good thing.
Would I rather a dozen of these bags ended up in landfill, or find 12 piles of poo in the beehive cells on the Garvellachs? Yes, I think I would.
For people confident and competent with dealing with their toilet needs outdoors, they may be unnecessary. But there are plenty of people who don't know what to do, and this could help them a lot. For commercial operators bringing people inexperienced in the outdoors into wild places, these would be an excellent idea to provide for their client's comfort.
These products could also have practical application on long crossings too.
Restop doesn't seem to be readily available in UK as of 2016, but alternatives might be the Green Loo and Travel John systems which seem to do essentially the same thing.
Mike Buckley, May 2010 - revised Jan 2016
Restop 2 - for solid waste - ready for use.
Restop 1 - for urine - two pouches per bag.
Shaped profile with a wide opening. Suitable for women as well as men.