How much money can you save replacing an old high-flow toilet with modern low-flow toilets? My house is old enough that we still have toilets that use about 13 liters per flush1 instead of the modern standard of 6 liters or less.
(I bet some readers landed here hoping to catch me using “literally” incorrectly. Maybe they have caught me. I’m literally flushing away something I have to pay for (water), but I’m not literally flushing coins or bills. It’s an important debate to have while I’m somewhere else.)
New dual-flush toilets use either 6 liters or 3.8 liters per flush depending on whether it is a big or small flush. This makes the water savings either 7 liters or 9.2 liters per flush. In my limited experience, low-flow toilets need more second flushes than my old toilets require. Combining this with the fact that small flushes are more frequent, I’ll call the savings an average of 8 liters per flush.
For my 4-person family, I estimate that we flush about 20 times per day on weekends and holidays (116 days per year), and about 12 times per day for the remaining 249 days per year. At 8 liters per flush, the savings add up to 42,464 liters or about 42 cubic meters per year.
With the exciting sewer surcharge of over 100%, I pay $3.25 per cubic meter of water. So my estimated savings on 42 cubic meters is $136.50 per year. Given the uncertainties in the water-saving estimates, we should probably say that the savings are between $100 and $200 per year.
The cost for me to replace 3 toilets is probably about $1000 for the toilets and the inevitable extra parts or replacement of a broken tool. Oh yeah, and I have to include whatever value I place on my labour for this type of work.
Overall, the payback time is in the 7-15 year range. That’s not fast enough to get me excited. I’d have to believe that the cost of water will rise faster than inflation, which seems likely. Another motivator is doing my part to protect our environment. It will take a burst of enthusiasm to overcome my natural laziness on this one.
1 Trying to find out how much water my toilets flush took a little while. They have no convenient markings of liters or gallons per flush. So, I was reduced to the ancient volume trick of length X width X height. The tank length and width were easy (46 cm X 16 cm). I had to actually watch a flush to see how far the water dropped (16 cm). But when the tank hit its low point, the bowl was still filling. So I had to estimate the volume of water to refill part of the bowl (20 cm X 16 cm X 6 cm). Then subtracting an estimate of the volume of stuff (technical term) in the tank, and using 1000 cubic cm per liter gave an estimate of 13 liters per flush. That’ll make you think twice about reading future footnotes.
Tackling the issue with little more understanding we may guess that you have two bathrooms and a powder room. The later is typically rarely used. Children's bathroom is used less (or will be used less within next 10 years) because the older they grow - the less time they spend at home. Therefore, if my guesses are correct you will catch most savings in the next 10 years by replacing the master bathroom, imho. BTW, if you choose good quality toilets you will rarely need to double-flush. My 2c.
ReplyDelete@AnatoliN: The pattern of use in my house is actually quite even right now. After the boys leave, use would be split fairly evenly between two. So, I'd have to replace two of them to get most of the savings. Do you have insight into how to choose good quality toilets? All the ones I've looked at seem to claim the same pressure.
DeleteIt's not so much about the pressure, as it's about the quality of porcelain: better ones are more slippery. This is much as I know. Friend used to work for a big distributor and she educated me a bit.That was at the other side of the pond, though.
DeleteAsked her for details:
Delete- price does not guarantee quality,
- traditional designs are more likely to have better quality due to inherent difficulties of producing pieces from porcelain
- slipperiness results from the quality of powder used to cover the toilet inner surface; powder quality vary significantly.
Bottom line: old brands, traditional shape and a hope that manufacturer has not cut corners.
(She worked for Kohler)
@AnatoliN: Thanks for the research. This doesn't sound very promising for new toilets. It's doubtful I could judge quality myself. I'd need an unbiased expert opinion.
DeleteMy experience with dual flush toilets has been a poor one. Over the span of 6 years with 3 toilets, I have had two of the flush mechanisms fail, and one of the refill mechanisms fail. The refill mechanism isn't a big deal, but trying to deal with the flush mechanisms can be a problem.
ReplyDeleteI should point out that these toilets were the toilets that came with a new house, which I am sure are close to the cheapest toilets that can be purchased.
I have replaced the failed dual flush mechanisms with generic replacements from Home Depot. This was a mistake. The have both failed. I received free replacements from the manufacturer with a new design, but they behave poorly.
When I recently finished my basement, I went with a single flush 1.6 gpf toilet. A single flush toilet is inherently much simpler with less chance of failure. I'm tempted to replace the dual flush mechanisms with simple single flush ones.
I realize I am only a single data point, and my experience may not be typical. But with all of the water that has been wasted with failing flush mechanisms, and the time spent trying to repair and eventually replace the mechanisms, I'm willing to sacrifice some efficiency for simplicity.
I'm willing to bet there are lots of people who have had dual flush toilets for years with no problems, but in the end I'd bet due to the added complexity of the mechanism, the failure rate MUST be higher.
@Returns Reaper: Thanks for sharing your experience. There's a lot to be said for simplicity. The added saving of dual-flush would disappear quickly with the problems you've had.
DeleteThe cost of water has been increasing by 9% in the city of Toronto in the past few years. With another 9% approved for this year. Way faster than the rate of inflation. So it might make sense for people living there.
ReplyDelete@Anonymous: I'm not much for predictions, but I'd be surprised if the cost of water grew slower than inflation in any part of the country, at least over a long period of time.
DeleteEven if you simply put 1 or 2 two large jars (glass, so they stay put) in your tank that will save you about 1 to 2 L per flush, over the course of time you will create savings without having to do the conversion that does not always have great results when installed. If your lazy this is a 2 minute job including the time to walk from the kitchen to the bathroom to this simple modification :)
ReplyDelete@Paul: Thanks for the tip. I'd heard of people putting bricks in their tanks, but I wondered about the brick eventually crumbling.
DeleteI've replaced a couple of my old toilets with dual flush models bought on sale at Home Depot 3ish years ago, and have not experienced the difficulties that AnatoliN has had. I did notice that one water diverter thingy (for the refil tube) never worked, and the other has recently stopped working, but it looks like the amount of water going into the refill tube instead of the toilet tank is relatively small. They were on sale for less than $100 so the price was definitely right too.
ReplyDeleteI don't have much plumbing experience, but the installation went fairly well, and there weren't any tools broken. Oh yes, the dual flush mechanism works very well, and the only time I have to flush twice is if I try to get away with a small flush where a big flush should have happened. Definitely worth the change (so far). As an added plus, the small powder room feels a touch bigger with the much smaller toilet tank.
The putting stuff in the tank recommendation is a good one. Just dont use something that might be water soluble, like a brick. Glass or plastic jar is fine.
ReplyDeleteI prefer to wait for old devices to break to upgrade. That way you reduce your incremental cap cost and therefore payback period. (Plus you could make the case this is more environmentally conscious, less wasteful) The problem is the parts of a crapper that will break are usually cheap ones like flappers, etc. Unless you actually crack a bowl. Taco Bell anyone?
@Guban: Your experience sounds more positive than Return Reaper's.
ReplyDelete@Anonymous: Thanks for the advice. Unfortunately, the one toilet in my house that is cracked is the one least used.
Here are my two cents worth on this subject. I have a family of 4 with two young children and we have two bathroom in our house. The upstairs toilet is (higher quality? at least I thought) Kohler that is about 10 years old to guess. The downstairs powder room, we replaced the toilet a couple of years ago to an economical but well researched(at least I thought model). I forget what it is called now, but toilets have a solids flush capacity. Make sure you can get the highest capacity possible! Our two young kids have greatly challenged this capacity quite often even on the brand new model. So any water savings with the dual-flush low flow toilet have been wasted on many many buckets of water dumped down the toilet trying to dislodge clogs. Not to mention wasted time trying various methods to open up the blockage. These low-flow dual-flush toilets just don't pack enough punch!
ReplyDeleteIf i had to do it over again I would buy a more efficient single flush with the biggest hole in it around.
@James: I wonder if better quality low-flow toilets exist or if it just isn't possible to make a low-flow toilet that can handle what kids throw at it.
DeleteIn my experience, mankind can't manufacture something a creative boy can't break :)
DeleteAlso worth including in the payback calculation are any rebates offered by your city for replacing high-flow models. For example:
ReplyDeletehttp://showmethegreen.ca/home/toilets/city-of-ottawa-toilet-replacement-program/
@Erick: Sounds like work to collect on such a rebate, but potentially worth it.
DeleteThe first rule of saving money: Buy the best you can afford. If you buy a cheapie toilet, you'll have the pursuant headaches and expenses of replacing parts. We have 2 Caroma toilets and have had no trouble whatsoever. They're made in Australia which, of course, invites observations about the perversion of being environmentally friendly with a product that's shipped, "literally," halfway around the world...
ReplyDeleteI replaced my 13litre toilets with quality 4.8litre versions a few years back. With a better siphon on the new models, they actually flushed better. Throw in municipal and provincial water reduction incentives and the toilets were essentially free. Problem was, the government campaigns at reducing water consumption were so successful, the city-run utility company raised the water rates to make up for the revenue shortfall.
ReplyDeleteMy go to source for these types of things is Consumer Reports magazine or now on-line. They are one of the few organizations that truly test consumer goods and rate them. They are skeptical of dual flush toilets for a variety of reasons and my personal experience has validated their reservations. The old mason jar solution is not bad and I tried it for some time but ended out having a lot of second flushes to clear the bowl - false economy and truly annoying with kids who never check. Finally followed Consumers recommendation and purchased (Lowes) an American Standard with their Champion 4 flush system which means the outlet from the tank is a 4 inch opening. It is amazing, works every time. Have now replaced a total of three toilets over three years. For one toilet we purchased the Champion 4 in a high end one piece design which was more expensive but it works even better and came with a soft close seat and lid.
ReplyDelete@Anonymous: Consumer Reports is a great source of information. I'll check out the "Champion 4 flush system".
DeleteConsumer Reports and solids / flush capacity ratings are a good place to start.
ReplyDeleteAlso, the comment about the higher quality construction is our experience as well. The sales pitch given to my folks when they bought a low(er) flow toilet years ago was to feel inside the trap / exit pipe. With most toilets, the glazing (smooth parts) only goes to the end of the bowl / beginning of the pipe. With the better low flow toilets, more of the pipe is glazed, possibly all the way to the floor. You should be able to reach inside a (new) toilet and feel how smooth the exit pipe is, and for how far. More smoothness = less resistance = better flush. There may be some factor to do with the path as well, but with any toilet, you still have to (literally) get around the trap...
My folks have had their low(er) flush toilet for a number of years, and have not had to double-flush any more than "usual".
Putting a brick or other object in the tank only reduces the amount of water and therefore the amount of flushing power. That's fine if the job is not too tough, but without any improvement in the "flow path" (ie. same old toilet with shoddy glazing), you can expect to have more double-flushes. You're trying to do the same job with less "power".
Also, I'm sure you've tried this, but would watching your water meter not show you how much water it took to refill the tank? Each little square on my Neptune water meter is 1L. Assume the tank refills to the same point each time, and don't try it while someone's taking a shower...