“If It’s Yellow, Let It Mellow” – Is It Worth It?

Disclosure: This post may contain affiliate links. Please read my disclosure for more info.

You might not want to read this post if you’re eating or drinking something.

When I was growing up, my parents strictly stuck with the “If it’s yellow, let it mellow” principle.

Even now when they’re financially stable, this principle still rules.

After Mr. FAF and I became homeowners, I’ve been wondering if I should do what my parents did and if it’s really worth it.

I started thinking about how much money I can save if I flush only once every four times I use the bathroom.

It does look a bit too much at one point and needs to be flushed.

I started digging and looking at the numbers.

According to the United States Geological Survey, each flush uses on average 3 gallons of water (1.6 gallons/flush for new toilets and 4 gallons for old toilets).

Federal plumbing standards now dictates that new toilets can only use up to 1.6 gallons per flush (GPF).

Since our house was built in the 1970s, I’d assume 3 gallons/flush.

On weekdays, let’s assume I only use the toilet roughly 4 times after work in the evening.

On the weekends, it’d be about 12 times a day.

The average price of water in the US is about $1.50 for 1,000 gallons.

In a year, there are 261 workdays and 104 days off. 

Let’s do the math. 

You can replace the numbers in red according to your usage of the toilet.

If I flush every time I use the toilet. 

On week days, I use the toilet 261 workdays * 4 flushes * 3 gallons/flush = 3,132 gallons or $4.698.

On days off, I use the toilet 104 days off * 12 flushes * 3 gallons/flush = 3,744 gallons or $5.616.

Total = $4.698 + $5.616 = $10.314 for 6,876 gallons

If I flush once every 4 times I use the toilet. 

On week days, I use the toilet 261 workdays * 1 flush for 4 times of using the toilet * 3 gallons/flush =  783 gallons or $1.1745.

On days off, I use the toilet 104 days off * 3 flushes for 12 times of using the toilet* 3 gallons/flush = 936 gallons or $1.404.

Total = $1.1745 + $1.404 = $2.5785 for 1,719 gallons

Money saved = $10.314 – $2.5785 = $7.73/year

Gallons saved = 6,876 – 1,719 gallons = 5,157 gallons/year

A family with 2 working adults

Depending on the number of adults in your family, the amount of money and water saved a year can be much higher than the figures above.

For example, if Mr. FAF follows my footsteps, we will be able to save:

Money saved = $7.73 * 2 = $15.46/year

Gallons saved = 5,157 gallons * 2 = 10,314 gallons/year


If I flush once every four times I use the toilet, I’ll be able to save $7.73/year. This is not a huge amount. However, considering I can save 5,157 gallons for the earth, that’s something I need to think about.

How about you? Have you thought about implementing “If it’s yellow, let it mellow”? If yes, have you noticed a reduction in your water bill?


How To Save On Furniture

5 Things We Refuse To Do To Save Money

How To Save Money With Substitutes

5 Reasons Why I Don’t Wear Makeup (Money Is Only One Reason)

Join Us For The Latest Update!


Join Us For The Latest Update!

43 thoughts on ““If It’s Yellow, Let It Mellow” – Is It Worth It?”

  • Saving water is great for the environment and I totally on board with it. However, for sanity reasons and younger kids in the household that may play with toilet water. We flush every time during the day. For nights, we don’t flush till the next morning because the plumbing is noisy in our household.

    We changes a couple of our toilets to water efficient toilets to save money and the environment.

    • I should probably get a new toilet too. Ours is really old. It’s been on my mind for a while. But the thought of hiring a contractor kinda stresses me out >_< I'm working on it. 😉

      • Have you looked into the tank efficiency things? Basically you replace the flap inside to make it not use as much water each time. We installed them ourselves and have been reaping the rewards for years now! I think each system only cost like $10-$15 too!

    • As Le T. Ly mentioned, water efficient hardware is the way to go. Low-flow toilets, showerheads, and sink aerators. While you’re at it, you can install some LED light bulbs too. Some up front cost, but pays for itself really quickly, even without any behavioral change.

      • Low-flow toilets, showerheads, and sink aerators sound like a great idea. Sometimes it does cost money to save money down the road 😉

  • Nice post. I love this analysis. I live in a high cost of water area. That sounds funny and I just invented it so you can go ahead and laugh at me. But because of this HCW I live in I’ve thought about saving water A LOT.

    There are a couple comments I can give you here. First, your toilet is most likely a 1.6 Gallon. You can check the base of the toilet where it meets the tank. The number is printed right there. If its a 3 then getting a new one isn’t a bad idea. Its not hard to do. Second, You can install a dual flush valve. Thats a valve that flushes one way for yellow and another way for solid. A quick read of product ads on Amazon tells me that the yellow flushes are 70% more water efficient. So on a 1.6 gpf toilet thats 1/2 gallon per flush.

    Now these are rough numbers but you could cut your water down to say 1200 gallons per year if you do each flush or 300 gallons per year if you do every 4th like you suggest.

  • Bahaha, I love that you wrote this! Mr. Adventure Rich is always searching Craigslist for toilets with less water capacity to avoid excess water waste. After living in drought-stricken California, we are water conscious and try not to use too much!

    • Thank you, Mrs. AR! I was in California last year and heard many people complain about water shortage. It’s alarming! $7/year doesn’t sound like a lot, but the amount of water saved can be significant!

  • Haha this is great 🙂 I only do this if I’m home alone because then I don’t really care. Ultimately like your analysis points out, it likely isn’t a big deal from a price perspective. From a water perspective, however, it’s a much bigger deal. It’s strange, but as a homeowner I have noticed myself become more conscious of our consumption of water and electricity than I ever was previously. Not sure if that’s a byproduct of some of the reading I’ve been doing on minimalism, etc. as of late or if it’s strictly related to home ownership.

    Regardless, preserving the water we have is always good in my good.

    • I’m with you on feeling more conscious of water and electricity after I became homeowners. I think we’re just more protective of the things that we own. When I saw the number of gallons saved per year, I was surprised because it sounded like a lot. I agree with you that preserving water is always a good idea! ^.^

  • If you live in a area with bad drought, then you should think about the environment. It’s not worth it financially. You will clean the toilet more often and that’s time and money.
    We live in Portland and we have plenty of rain, but a lot of people still put the environment first.

    • I think it’s great that many people in Portland want to protect the environment. I know Portland is also well-known for having a lot of green buildings too. ^.^

  • It take like 10 seconds to do a quick swipe with the toilet cleaning brush twice a week…what’s the big deal?

    I pee like 10 times a day or more so it would be very wasteful for me to flush every time!

  • Hahaha I thought of something totally different when I read the topic. I just came over from Freedom is Groovy’s and I was like…what? Who is mellow and yellow???? Lol I’m so bad!

    Do you guys have low flow toilets? That saves a little bit of money and water compare to older versions.

    • We have a low flow toilet installed by the previous owner in the half bath. But the rest of the toilets must be from the 70s or 80s @_@. I think we need to buy new ones soon.

      I read Freedom is Groovy’s post about Asian Americans this morning too. And I know what you were thinking (I think) ^.^ 😀

  • I want to see this with cleaning product costs calculated in! Or, maybe I just use toilet bowl cleaner more than I should? Because that definitely ups the cost/lowers environmental savings.

    How often do most people use toilet bowl cleaner?!

    These questions will haunt me.

  • Haha I love this great analysis! I pee constantly but I only flush about twice a day to save water/money. I love now knowing how much water I could be saving yearly by not flushing every time I go. I do flush when I think someone else might be using my bathroom, unless it’s one of my environmentally friendly friends who is coming over, since I know they won’t mind. It’s great to have friends who care about the environment too and want to help your endevear. I put one of those toilet bowl cleaners that you just stick on the side and I haven’t had any problems with yellowing, but the toilet is getting flushed daily too which might help also. Great post!

  • Thanks for doing the math. I didn’t realize it was that little that you would save for the entire year. We usually flush, just not during sleeping hours. We also try to double up on toilet use (so when we come home from work, we both pee before we flush). So at least every little helps the wallet and the environment that way.

  • You know it’s funny how perspective and situation change thing. We live on a well and a septic system in a non drought area (usually). As such I have little to no environmental or water table impact from the facilities. My costs are also largely sunk. As such this never even crosses my mind to skip a flush, except for fear of waking up kids sometimes at night. . but if I lived somewhere I paid for water or where it didn’t just go right back into my land down stream I’d probably behave differently.

  • I always flush! AND I ‘invested’ in a new toilet. It took me a while though because I was frustrated with the pink ring around the toilet and how it would get dirty so quickly. AND not flush very well (sorry). I consulted a plumber and he said my toilet was old and couldn’t fix that problem. The toilet was about 9 years old I think.

    So then I sold things on Craigslist and started putting money towards my “Toilet Fund” and once I saved enough to have it installed, I bought the Toilet and paid for a contractor to put in a new toilet for me. In total I think it was $250 but so worth it because now my toilet lasts longer between cleans.

    I hate cleaning the bathroom the MOST.

  • We replaced the toilet in our Master when it started to leak. We changed the guts twice and it kept leaking. Previously, I threatened to put a brick in the tank to use less water. I loooove it and want to do the other bathrooms. Can’t quit justify it yet because they are used so infrequently and don’t leak.

    For people who want to do this for eco reasons, you can also flush your toilet with cold water while the shower/tub heats up or even water from cooking.

  • Haha this was a great read thanks for exploring in depth. I’ve often wondered the same things. We usually leave it a few times, unless guests are coming over, mostly for lower water usage. If ever we have to replace a water fixture, low flow will be the way to go!

  • We don’t flush each time but its because we like to save water. Our tank only holds 2000 gallons and we have to pay $180 to fill it up. Also our washer is old and fills up no matter what level is selected. So we only wash when we have enough to fill it to the top in an effort to conserve. For the past 6 months we have only ordered water once and have been able to fill the tank with rain water.

  • Oh, my. I don’t think I could handle this; for some reason I’m very icky when it comes to these things. If anything, I’d say it can be done for the environmental reasons, but I agree that going with low-flow technologies seems like a good middle ground.

    There’s also dual-flush toilets today that have a “light” flush for no. 1 and a “full” flush for no. 2.

  • I had a friend whose family didn’t flush the yellow at night – but that was to prevent people from waking up, not to save the money. There are low-flush toilets out there and stuff… I’m struggling to get my family into composting with city-provided bins 😛 I don’t think they’d go for this. Plus I’d be worried about losing the habit of flushing every time and missing… a more important flush!

  • We don’t always flush the toilet. I would estimate every other time we use the toilet, we would flush with the exception of taking a #2 where we flush immediately.

  • You know we do this in our house as well. Growing up in my house, we rarely flush(for #1) unless it was pretty yellow? (Not sure the word but you get the point) However the stains were actually pretty obvious. So eventually we evolved to the point where you just use your visual judgement, as long as it’s not too yellow!

  • Well, even from the perspective of the gallons of water used, the flushed water does make its way to a treatment plant and gets treated so that it eventually becomes water again. It’s not like that water is gone from the earth forever.

  • How does flushing a toilet harm the environment? The water doesn’t leave the earth when you flush.

    I would also agree that your cleaning costs are going to increase by letting it “mellow”. I can definitely see how dumping more cleaning chemicals down the drain could have an environmental impact, if they are not treated correctly at the sewage plant.

    • Not a lot, but in the aggregate? It can add up because every gallon has to be first treated to make available (since it would cost too much to not use potable water, so one stream it is) and then treated (because you don’t want black or grey water released back into the system, that is seriously gross) before being released back into environment. It really depends on where you live.

      • Bacteria clean the water at the sewage plant, and I’m sure they would love the extra human waste to feed on. Cleaning chemicals, not so much.

        It may cost humans more money to provide more potable water to consumers, and to treat that water after use, but assuming we aren’t releasing contaminated water back into the environment, I still don’t buy the argument that using more water harms the environment.

  • We are totally down with this! We have been forgoing “yellow” flushing to save the earth and money. For a family of 4, who it homeschooling…that’s a heck of a lot of water we are saving! ;D Hoping to retire soon too from all the savings in all aspects of our lives! Woo hoo!

  • Dear FAF,

    We have a low flow, dual flush valve and still “let it mellow”.

    I also save bath water (for a day or two, otherwise I let it go to minimize humidity) and use it to flush the toilet (i hang a bucket in the shower where no one can see). I’ve noticed a decrease in our electricity bills due to this.

    I keep a spray bottle with a vinegar/water mix in it and spray the toilet and sink down when required. We have really hard water so it helps with build up too. 1 Gallon of vinegar costs $1.60 and I only buy a few a year (I clean my whole house with the stuff) so it’s less than 1 cent a “cleaning” and I don’t even need to scrub (I just let it sit overnight).

    I love that you’ve written about this. Keep the great topics coming.

    Besos Sarah.

  • Some water companies offer rebates if you purchase a new water efficient toilet (1.1 gpf or less). Might be another avenue to save money, be environmentally friendly and get a new toilet for cheap.

    You could still let the yellow mellow to compensate for all the flushes after Mexican food night…

  • I love this! It’s frugal nerdiness at its finest! My roommates and I did this in college to save money but we never did a thorough analysis. We just figured we would save money and as broke college students, we were cheap and stingy.

    I think you’re right that saving water is probably the most important element to this experiment.

  • I love it when someone actually does a breakdown like this. With two young boys, our toilets have gotten plenty of use and abuse in recent years. We often let the yellow mellow as they say — to the point where we sometimes have to remind them to flush it down when it’s brown.

    The money isn’t much, but clean water is something we need to preserve. I recently read about breweries in California doing everything they could to reduce water usage in the community so they would have enough to make beer for them!

    When we built a home, I special ordered four dual flush toilets — the little flush used only 0.8 gallons.


Leave a Reply

Your email address will not be published. Required fields are marked *