Join Date: Sep 2008
Location: Victoria B.C. Canada
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Re: Composting Toilets vs. Holding Tank
Well the toilet is only a small part of the expense. It will really depend on if you can find space for a stock size holding tank. Holding tanks are going to start at about $500(custom goes way up from there), vented loop at $100, Y valve at $50, hose is about $10 a foot(depending on set up, but figure at least 15 feet), macerator pump $200, deck fitting at $100 and figure at least $300 more in miscellaneous fittings and parts.
I don't see how you can get in a normal set up for under a grand even with your toilet, but toilets are only about $300 for a usable one. (keep in mind when yours needs to be rebuilt often easier and just as cheap to replace) You have to use quality parts, such as top of the line Trident Hose as anything else is going to stink in a few months or at least 2 years. You don't want to have to re do the hoses any time soon.
Maybe where you live but not here - Victoria B.C. Canada. We sell holding tanks from about 129 for a small (6 gallons) to much larger - 30 gallon under 300. There are about 20 or so different sizes. These are thick walled tanks designed as holding tanks though many use them for water. These prices include 3 spun in fittings in the locations the buyer chooses. Vented loops are in the 25 dollar range for 1 1/2" and less for 3/4". The hose (Premium sanitation) runs from about 8 to 11 per foot. The deck fitting is under 30 - same as a water or diesel fill with a different name on it. Y valves are not necessary. If everything goes into the tank it is less likely to turn into hard to remove cement, especially for those who only use the boat on weekends. From the tank to the deck outlet and another outlet to the seacock for overboard pumpout either with an electric macerator or a manual diaphram pump, either bought for under 150.
There is another even simpler and less expensive way if space allows - a gravity tank. The tank has to be above the waterline and behind the head is the best place. The deck pumpout fitting should be directly above the seacock but this isn't absolutely necessary - it does allow easy clearing it the seacock becomes restrictive, but people using this system rarely have this problem. Everything goes into the tank. If offshore the seacock is left open. If inshore it remains closed and you can either pumpout as normal or open the valve offshore where it is legal. You do not need a large boat for this, just some space in the correct place. It fits on my CS27 fine and I know of several Vega 27 owners with gravity tanks that they are very happy with.
Living aboard in Victoria Harbour