Had a similar headache in one of my older rental units. Tried swapping in a dual-flush kit on a ‘70s tank, thinking I’d save on the water bill and do my bit for the environment. Long story short, it ended up being more trouble than it was worth—the half flush just didn’t have the oomph, and my tenants started complaining about double flushing or clogs. Ended up fiddling with the chain and float for weeks, but nothing really fixed it.
Honestly, I get the appeal of keeping the old fixtures, especially if you like the vintage look or you’re trying to avoid a bigger job. But after factoring in all the time and parts, I would’ve been better off just replacing the whole thing. The newer toilets are designed for those low-volume flushes and seem way less finicky. Plus, you don’t have to worry about leaks or overflows from an old tank not sealing right... which is a whole other headache no one wants.
I guess if someone’s really attached to their old toilet, they could keep tinkering, but from what I’ve seen, it rarely works out as planned.
- Totally get where you’re coming from. I tried a similar retrofit on a late-60s toilet and it just never worked right—half flush was basically useless, and the full flush wasn’t much better after all the fiddling.
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Couldn’t agree more. The amount of time spent tweaking old hardware adds up fast.“after factoring in all the time and parts, I would’ve been better off just replacing the whole thing.”
- One thing I noticed: those older tanks are just built for a different kind of flush. You can swap in all the modern kits you want, but if the bowl and trapway aren’t designed for low flow, it’s always going to be a struggle.
- If you’re set on saving water, honestly, newer toilets are way less hassle. The only exception I’ve seen is if someone’s really into restoring vintage stuff for looks—then maybe it’s worth the headache... but that’s a pretty niche case.
Yeah, I’ve run into this a bunch—trying to get a dual-flush kit to work on an old toilet is almost always more trouble than it’s worth. Those older bowls just aren’t designed for the quick, low-volume flushes that modern kits rely on. You end up with weak half flushes that don’t clear anything, and even the “full” flush can be underwhelming. I’ve had customers get frustrated after spending hours swapping out parts, only to have to double-flush every time anyway.
Honestly, unless you’re really attached to the look or there’s some sentimental value, it’s usually better to just bite the bullet and replace the whole thing. Modern toilets are engineered for efficiency from the ground up, so you get the water savings without all the fiddling. Plus, you’ll probably save yourself a lot of time and headaches in the long run.
One thing I will say—if you’re dead set on keeping the vintage tank for aesthetic reasons, sometimes you can get a little more oomph by adjusting the float or using a different flapper, but it’s always going to be a compromise. The trapway and bowl shape just aren’t made for low-flow performance. I’ve seen people try to drill out jets or tweak internals, but that’s a slippery slope and can actually make things worse.
Funny enough, I once had a client who was determined to keep their avocado green toilet from the ‘70s. We tried every retrofit kit under the sun. In the end, they gave up and just used it as a decorative piece in their garden... probably the best use for it at that point.
Long story short: retrofits are rarely worth it unless you’re restoring for looks. If function matters most, newer toilets are just way less hassle.
Had the same issue with an old Kohler—tried a dual-flush kit and it was just a waste of time.
That’s exactly what happened. Ended up swapping the whole thing for a new Toto and haven’t looked back. The old bowls just aren’t built for it, no matter how much you tweak.“You end up with weak half flushes that don’t clear anything, and even the ‘full’ flush can be underwhelming.”
Honestly, I’ve seen this play out a dozen times—those retrofit kits just don’t mesh with older bowls. The water path and bowl design matter more than people think. Did you ever try adjusting the float or flapper? Sometimes you get lucky, but usually… not so much.