Not all toilets do wear out in 5-10 years
Everything has a lifespan, especially if it has a motor and/or moving parts...in fact, there are very few things on a boat that last much longer than about 10-15 years. Winches wear out...sails wear out. And so do toilets...but because houshold toilets last for decades without any maintenance except possibly a new ball kit every 10-15 years, people expect the same to be true of marine toilets. What they fail to realize is that household toilets have no moving parts, whereas marine toilets are working machinery that does have moving parts...and those parts wear. And just like most other things, the cheaper the toilet, the shorter its life-span due to lower quality materials. However, maintenance or lack of it can double the lifespan of even the cheapest toilets or cut the lifespan of the best toilets in half. The pump, seat and lid are actually the only parts of the toilet that do wear out...china bowls don't. But because complete toilets almost always cost less than replacement pump assemblies sold by themselves, it's often more cost effective--and easier--to just replace the whole toilet. A piston/cylinder pump has moving parts...and any time there are moving parts, there's also wear on those parts. Lack of proper lubrication increases that wear on both the replaceable rubber parts and the housing. Salt and grit scratch and score the inside of the pump cylinder...dry friction of seals and o-rings against it till it primes wears both the seals and the inside of the cylinder...and because humans aren't precise machines that put even pressure on the pump handle, the wear is uneven...eventually the cylinder is no longer perfectly round, which prevents new perfectly round seals from sealing any more. That wear is even worse if the rubber parts are dry and hard. Hardware also ages...working it takes its toll...cheaper materials age and wear out faster. Average lifespan of a manual toilet costing under $150 is about 5-7 years...can be stretched another couple of years with scrupulous maintenance--lubrication and rebuilding every 2-3 years). However, when a rebuild kit is more than half the price of the toilet, total replacement is often more cost effective. Average lifespan of a manual toilet costing $150-200 is about 7-10 years. Average lifespan of a manual toilet costing $200-$500 is about 20-25 years, providing the toilet is maintained, at least 10 even if it's not. Lifespan of manual toilets costing $500-$1000 is measured in decades, or even centuries. A rebuild kit for one of 'em may cost almost as much as a cheap toilet, but is a worthwhile investment every 10 years or so.
