Do You Need A Pressure-Flushing Toilet? Maybe Not.

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Pressure-Flushing Toilets are a new thing, but maybe not a thing you need.

We still have residual problems with our sewer line.  The part by the road is all clay pipe and the Authority refuses to replace it, but offers to clean it out with a roto-rooter for free, if they become clogged.  I also own my own roto-rooter now, and can run it through the lines in the house periodically to remove tree roots, rust and scale (from the few black-iron pipes we still have) and the occasional non-woven spun fiber clog.  The new PVC drain pipe installed by the previous owner works OK, but goes slightly uphill where the two trees are (since removed) likely because roots moved them.

Also, it seems the plumbers decided to connect the toilet in series with the spa tub and shower, such that if you flush the toilet while someone is in the shower, it may not flush properly.  The only fix for this is to dig up the back yard, dig under the slab and install new drains for the toilet, tub, and shower that each go directly to the main drain, rather than connect in series.  I may end up doing this, eventually.  It is not as onerous as it may first seem, as all three connections are no more than a few feet from the edge of the slab.

Sometimes, it seems the system just "hiccups" and when that happens, I put a temporary plumber's plug into the drain of the shower (after removing the shower drain screen) and then fill the spa tub with 100 gallons of water.  Once full, I open the drain and the pressure of all that water seems to blow things out.

I also put old soup cans over all the drain "vents" in the roof (and there are like five of them).   I punched a hole in the bottom of each can to let air in.  It seems that the roof vents were open to the air, but also open to the pine needles, leaves, and other debris, as well as squirrels and their nuts.  They also make a nice plastic cap for these, for sale at Lowe's and Home Depot, and I may end up getting those eventually.   But a clot of pine needles in the roof vent(s) can prevent your drains from draining.

Since I put on the soup cans, it seems we have fewer "hiccups" in the system.

Mark had the idea of buying a pressure-flush toilet to help the situation.   At first, this seemed like a good idea, as the pressure would force things through.  But on the other hand, if there was a clog, it might also force "things" up through the shower drain like a fountain, which would not be pleasant.  We have had things back up into the shower in the past, and that isn't pretty.

I looked into it, as it seemed like it might help.   But when I visited the flushmate site, realized that our present toilet could not be "converted" to a pressure toilet, and what's more, the point of a pressure toilet was to save water, not improve flushing.    So we would have to spend more money to get this toilet, and it might not work as well as our present "gravity feed" toilet does.  With our drain situation the way it is, it pays to flush twice rather than flush once with a fancy toilet that uses less water.  More water moves things down the line, when your sewer line is essentially flat.

There are also other issues.  As folks in this discussion group noted, the pressure-type toilet costs more and may need more maintenance.   In a gravity-feed toilet, the main seals are under the pressure of the water in the tank - about 18" of water pressure or "head".   So the chance of the main toilet-to-tank seal leaking is small.  But in a pressure feed toilet, the entire thing is under house water pressure, which in places like Fairfax County, Virginia, can be as much as 100 psi - a water pressure regulator may be in order!

Tellingly, Amazon sells a replacement "tank" by itself to "fix the leak" problem with these systems.  That says a lot to me. 

How do they work?  It isn't exactly rocket science.  The plastic tank is full of air.  When water enters, it is at system pressure (50-100 psi, depending on your local water company or well pump) which pressurizes the air.  The tank contains about 1 to 1.6 gallons of water (far less than a gravity-feed toilet) and the rest of the tank contains air, now compressed to water system pressure.  When you flush, this smaller quantity of water is forced out at system pressure (again, 50-100 psi) which is a lot more force than a gravity-feed toilet has (about 18" of head, or less than 1 psi).   Needless to say, this forces things down the pipes more resolutely.

Because of this, though, you cannot retrofit a gravity-feed toilet with a pressure-feed system, even though it looks like the pressure-feed system fits into a standard tank.   The simple reason is, the pressure-feed system uses a different bowl plumbing and if you attached a pressure-feed tank to a gravity-feed bowl, you would  likely get a face full of water with every flush, or an inadequate flush, if at all.


Exploding toilets - without having to light your farts!


There are some other minor issues as well.  Apparently some older versions of these toilets have been known to explode, at least under certain circumstances.   Of course, this was for an earlier model unit which has since been recalled.  Seems the two halves of the plastic pressure tank would come apart, which could cause the porcelain tank to blow up (maybe it is time we got away from porcelain toilets?  Just a thought).  Some folks were injured by flying porcelain shards.

Presumably, the design has improved since then, and exploding toilets are now a thing of the past.

While saving water might seem like a good thing, it is not a major expense for us at the present time. Our combined water, sewer, and trash bill is about $70 a month or less (and this is not much above the minimum charge we would receive even if we used no water whatsoever).  Watering the lawn and washing the car are the big offenders in the water bill department.  Flushing the toilet might come in 4th or 5th behind washing dishes and clothes.

But we may revisit this if, down the road, we re-plumb the toilet so it has a direct line to the sewer.  In the meantime, I don't see the pressing need or the savings.  The cost of the toilet would take years to realize in terms of reduced water bills.  And in our situation, power-flushing might actually backfire in our faces - quite literally!