Tankless water heaters: casing leaks versus connection leaks

“Hoses at least give you some warning, but valves seem to fail all at once... not a fun surprise.”

Man, I hear you. I tried to save a few bucks by ignoring my crusty old shutoffs, thinking, “Eh, they’ve lasted this long.” Next thing I know, I’m on my knees with a towel, cursing the day I ever trusted a 30-year-old valve. At least when a hose starts to bulge, you get a heads-up. Valves? One minute they’re fine, the next you’re mopping up. If you’re on a budget, I’d say swap those valves out during a slow month - beats paying for water damage later.

“Valves? One minute they’re fine, the next you’re mopping up.”

Yeah, I learned that the hard way too. I figured, if it ain’t broke… but then it was. Honestly, I’d rather deal with a slow drip than a surprise flood. At least you can spot a drip before it wrecks your floor.

Drips are annoying, but at least you’ve got a fighting chance to catch them early. I get what you’re saying here:

I’d rather deal with a slow drip than a surprise flood.

What’s everyone’s experience with those connection leaks versus box drips? Which one’s done more damage in the long run? I’ve seen slow leaks rot out cabinets before anyone notices. At least with a sudden failure, you’re forced to deal with it right away… but maybe that’s just my luck.

Man, I’ve seen those sneaky drips under the sink just chew up a cabinet floor before anyone even notices. It’s wild how something so small can do more damage than a big, obvious blowout. At least with a flood, you know right away and can start mopping up... but that slow rot smell? That’s a nightmare. I’d almost take the drama of a sudden leak over the silent destroyer any day.

Yeah, those slow leaks are like termites for cabinets - just munching away while you’re blissfully unaware. I once had a tenant swear there was a “weird musty ghost” in the kitchen, only to find the particleboard under the sink was basically pudding. Give me a noisy pipe burst any day... at least it’s honest about ruining your evening. Those sneaky drips? They’re just rude.

Give me a noisy pipe burst any day... at least it’s honest about ruining your evening.

Honestly, I’d take the slow leak over a burst, but only because of water waste. Those tiny drips add up - bad for your bill and the planet. Still, I get what you mean about the “musty ghost.” Mold from hidden leaks is a nightmare. At least a big leak gets your attention before the cabinets are toast.

Mold from hidden leaks is a nightmare. At least a big leak gets your attention before the cabinets are toast.

Totally get that. I’ve seen folks ignore those slow drips for months, thinking it’s “just a little water,” and then bam - warped wood, musty smell, and a repair bill that’s way worse than fixing a burst pipe. At least with a burst, you know you’ve got to act fast. But yeah, those sneaky leaks are brutal for your wallet and the environment... hard to pick the lesser evil.

- Had a slow leak under my bathroom sink once - barely a drip, but it went unnoticed for who knows how long.
- By the time I found it, the cabinet bottom was soft and moldy.
- Honestly, I’d take a big obvious leak over that any day.
- At least you know there’s a problem right away and can shut off the water.
- Those sneaky drips just quietly destroy everything... and the musty smell never really goes away, no matter how much you clean.
- Makes me check under every sink way more often now, just in case.

Honestly, I get what you mean about the sneaky drips being a pain, but I’d still rather deal with a slow leak than a big one. A major leak can flood your whole cabinet or even the floor in minutes if you’re not home. At least with a drip, there’s usually time to catch it before it does serious damage - assuming you check once in a while.

At least you know there’s a problem right away and can shut off the water.

True, but if you’re out or asleep, that “obvious” leak can do way more damage in less time. Had a friend whose supply line burst while he was at work... came home to water everywhere, ruined flooring, drywall, the works. Insurance covered some of it, but it was still a nightmare.

I guess both suck, just in different ways. Now I’m paranoid about both types, honestly.

I totally get the paranoia - after dealing with a slow drip under my kitchen sink for months (didn’t notice until the wood started warping), I’m always checking under there now. But honestly, I think the big leaks are scarier just because of how fast they can wreck everything. Like, you can go from “huh, is that a puddle?” to “why is my baseboard floating?” in no time if a supply line pops.

But here’s the thing: those sneaky drips can still do a ton of damage if you’re not looking for them. Mold, warped cabinets, even pests if it goes on long enough. And insurance doesn’t always cover slow leaks if they decide it’s “neglect.” That’s what freaks me out - what if I miss something tiny and it turns into a huge repair bill?

I started putting those cheap water alarms under my sinks and behind the washer. They’re like $10 each and just screech if they get wet. Not perfect, but at least I’ll know if something starts leaking while I’m home or asleep. Has anyone tried those smart shutoff valves? They’re pricier, but I keep wondering if they’re worth it for peace of mind. Or is that overkill?

I guess at the end of the day, both types of leaks are bad news, just in different ways. The slow ones are sneaky and expensive over time, but the big ones are like instant disaster. Makes me wish there was a way to just waterproof the whole house... but that’s probably not in the budget.

- Seen too many folks ignore "just a drip" until it trashed their cabinets - slow leaks are silent killers, no joke.
- Water alarms help, but they're only as good as your batteries and how often you check them.
- Smart shutoff valves? Mixed feelings. They work, but installation can be a pain, and sometimes they false-trigger. Had one client’s valve shut the whole house off over a little condensation.
- Honestly, nothing beats just poking around under your sinks every couple weeks. Not glamorous, but it works.

Leaks at the connections are usually worse in my experience - those can go from a drip to a full-on spray if a fitting fails. Drips from the box (like the shutoff valve) tend to be slower, but both can cause serious damage if ignored. I keep a flashlight under the sink just to make it easier to check every week or two... not fancy, but it’s saved me more than once.

Drips from the box are sneaky, but man, a connection leak is like a ticking water bomb. I had one go from “eh, that’s just a tiny drop” to “why is there a fountain under my sink?” in about two hours. Still, I’m paranoid about both now... I even keep old towels under there just in case. The flashlight trick is clutch - beats crawling around with your phone in your mouth.

I had one go from “eh, that’s just a tiny drop” to “why is there a fountain under my sink?” in about two hours.

That right there is the stuff of plumbing nightmares. I’ve seen more kitchen cabinets ruined by “just a tiny drop” than by anything else. Drips from the box are sneaky, yeah, but at least they usually give you some warning - little puddle, maybe a musty smell. Connection leaks though? Those things escalate faster than my dog when he hears the treat bag. One minute it’s a drip, next thing you know you’re ankle-deep and wondering if you should start building an ark.

I’m with you on the towels. I’ve even used baking sheets under sinks before, just to catch the first wave. And that flashlight trick? Game changer. Crawling around with your phone in your mouth is basically a rite of passage, but man, it’s overrated. Give me a proper flashlight any day.

If I had to pick my poison, I’d take a box drip over a connection leak every time. At least with a box drip, you’ve got a fighting chance before it turns into Niagara Falls.

- Had a tenant call me once about a “little drip” under their bathroom sink. Figured it was nothing urgent, but by the time I got there, the vanity was basically mush and the laminate floor was starting to buckle.
- Connection leaks are my nemesis. They go from zero to disaster in no time, especially those sneaky ones at the shutoff valves.
- I keep a stash of old towels and even a couple of plastic trays just for these situations. Not glamorous, but they’ve saved me more than once.
- Honestly, I’d rather deal with a box drip too. At least you get some warning before things go sideways. Connection leaks? Blink and you’re in trouble.

I swear, those sneaky shutoff valve leaks are like ninjas - silent but deadly. I once had a “just a drip” call that turned into a full-blown cabinet demolition job. Anyone else ever try those flexible supply lines with the built-in gaskets? Worth it, or just another thing to fail down the line...

I’ve used those flex lines with the built-in gaskets a few times. Honestly, they’re super convenient and quick to install, but I’ve seen the gaskets wear out faster than I expected. If you’re in a spot where you can check on them every now and then, they’re fine. For anything hidden or hard to reach, I’d stick with the old-school stuff - less to go wrong down the road.

For anything hidden or hard to reach, I’d stick with the old-school stuff - less to go wrong down the road.

- I get where you’re coming from, but I actually trust the newer flex lines more than soldered joints these days.
- Had a soldered copper joint fail behind a wall last year - total nightmare to find and fix.
- At least with flex lines, if there’s a problem, it’s usually right at the connection and easy to swap out.
- Gaskets do wear, but honestly, I’d rather deal with that than a hidden pinhole leak in copper.
- For me, the peace of mind comes from being able to see and reach the connections, not necessarily the type of line.

Had a flex line blow out under my kitchen sink once - water everywhere, but at least I could see it and shut it off quick. Still, I get nervous about those little gaskets. They always seem like the weak link, just waiting to give up on a Sunday night.

For me, the peace of mind comes from being able to see and reach the connections, not necessarily the type of line.

Totally agree with this. I’d rather have something I can actually get to, even if it’s not “old school.” Chasing a leak behind a wall is my idea of a bad time. Give me a drip I can spot and fix over a mystery puddle any day. Hidden leaks are like plumbing horror movies - never ends well.

Man, hidden leaks are the worst kind of surprise - like the plumbing version of finding out your car’s been dripping oil for a month. At least with a flex line or a gasket under the sink, you can spot the mess right away (and maybe invent some new curse words while you’re at it). But when it’s behind drywall? That’s when things get expensive, fast.

I’ve always wondered why those little rubber gaskets seem to be the first thing to go. Is it just age, or do they secretly hate us? I started checking mine every couple months after a friend had a slow leak behind his dishwasher that warped half his kitchen floor. Now I’m paranoid about anything I can’t see.

Honestly, I’ll take a visible drip over a hidden one any day - even if it means crawling under the sink and getting soaked. At least you know what you’re dealing with... usually.