Rainwater toilets and greywater showers: City tries new water-saving tricks

Rainwater Filtering: Mesh vs Cartridge - Worth the Switch?

Mesh filters are kind of the unsung heroes, right? They just sit there, catching the big stuff, asking nothing in return except maybe a rinse every now and then. I totally get what you mean about UV feeling like overkill for toilets and laundry. Unless you’re planning to brew tea with your cistern water (not recommended), mesh does most of the heavy lifting.

Now, cartridge filters… I did give those a go last winter because my partner was convinced mesh alone was “gross.” The step-by-step: I swapped out our basic mesh filter for a 5-micron cartridge. Installation was straightforward - just had to make sure the pressure didn’t drop too much. Here’s what I noticed:

1. Water looked a bit clearer, but honestly, for toilets and laundry, it’s not like I’m inspecting the flush.
2. Cartridges clog up faster than mesh if you’ve got lots of fine silt or pollen drifting in. In spring, I was changing them every 3-4 weeks. Not exactly my idea of fun.
3. Cost-wise, mesh is basically a one-time thing (unless it gets damaged), while cartridges add up over time.

I’ll admit, the cartridge felt more “high-tech,” but at the end of the day, my socks came out just as clean and nobody’s noticed any difference in bathroom performance (if that’s even a thing). If you’ve got super fine sediment or are picky about water clarity, maybe it’s worth it. But for most city roofs and regular rainwater use, mesh seems to hit that sweet spot between low-maintenance and effective.

Honestly, unless you’re dealing with some gnarly debris or have a lot of people using the system, I’d save your cash for something more exciting - like a rain barrel with a built-in frog slide or something equally unnecessary but fun. Stick with what works; sounds like you’ve got it dialed in already.

Cartridges clog up faster than mesh if you’ve got lots of fine silt or pollen drifting in. In spring, I was changing them every 3-4 weeks. Not exactly my idea of fun.

That’s been my experience too - cartridges just don’t last in high-use setups, especially with a few tenants in the building. Have you ever tried combining both, like mesh as a pre-filter and cartridge after? Wondering if that might cut down on maintenance or just add more hassle.

Honestly, I’ve seen the mesh + cartridge combo backfire if you’re not careful.

“Have you ever tried combining both, like mesh as a pre-filter and cartridge after?”

I get what you’re saying about the mesh + cartridge setup being a pain if you’re not on top of maintenance. I’ve only messed with it in smaller residential setups, and even there, the mesh gets gross fast - especially after a heavy rain. The idea sounds good on paper, but unless you’re ready to clean that mesh like clockwork, it’s just more work.

Honestly, I’ve had better luck with those pleated cartridges that have a bigger surface area. They seem to last longer between changes, and you don’t get that sudden pressure drop when they start to clog up. Sand filters are solid too, but they’re kind of overkill for most home systems unless you’re dealing with a ton of runoff or really fine silt.

One thing I noticed: if you use a sloped catchment or leaf diverter before the tank, you can cut down on the big debris before it even hits your filter setup. Not perfect, but it helps keep things running smoother.

That’s a good point about pleated cartridges - they really do buy you more time between maintenance cycles, especially if you’re dealing with variable water quality. I’ve noticed, though, that if you get a sudden influx of organic debris (like after a storm), even those can clog up faster than expected. Sometimes it feels like no matter what filter you use, the real trick is in the pre-filtration.

Leaf diverters and sloped catchments definitely help, but I’ve seen setups where folks skip regular gutter cleaning and end up with a mess anyway. It’s amazing how quickly biofilm can build up if you let things slide for even a week or two. Have you tried any of the newer self-cleaning pre-filters? I’m curious if they actually reduce hands-on maintenance or just shift the problem elsewhere.

Also, with city systems experimenting with rainwater for toilets and greywater for showers, I wonder how they’re handling the maintenance side at scale. Are they relying on automated monitoring, or is it still mostly manual checks?

I’ve been burned by biofilm before - missed cleaning my gutters for just a couple weeks and ended up with this slimy mess in the first flush diverter. It’s wild how fast it builds up, especially in humid weather. I tried one of those self-cleaning pre-filters last year (the kind with the rotating brush inside). Honestly, it helped with leaves and big stuff, but the fine gunk still made its way through. Maintenance was easier, but not hands-off like I hoped.

As for city systems, from what I’ve seen in some pilot projects, there’s a lot of remote monitoring now - sensors for flow rates and pressure drops to flag clogs. Still, someone’s gotta go out and physically check things when alarms go off. Doesn’t seem like there’s any true “set and forget” solution yet, at least not if you want to avoid surprises.

Yeah, biofilm is a sneaky one - seen plenty of folks surprised by how quick it builds up. Those self-cleaning filters are decent for the big stuff, but you’re right, the fine gunk always finds a way. Even with all the new tech and sensors, there’s still no magic fix. Maintenance just keeps finding ways to stay interesting, doesn’t it? I guess the “set and forget” dream is still a ways off for most setups.

Yeah, I’ve noticed the same thing with my rainwater system - biofilm just creeps in, no matter how careful I am. I wonder if switching filter materials more often would help, or maybe tweaking the flow rates? It’s wild how even “smart” tech still needs old-school elbow grease.

Yeah, I’ve noticed the same thing with my rainwater system - biofilm just creeps in, no matter how careful I am. I wonder if switching filter materials more often would help, or maybe tweaking th...

I get what you’re saying about “elbow grease” - even the best systems need hands-on work. But honestly, I’d be careful about just swapping filter materials more often. Sometimes, over-handling can actually make things worse by disturbing settled gunk and spreading biofilm around. Instead, I’d focus on a strict cleaning schedule and maybe even UV sterilization if you can swing it. I’ve seen folks try to tweak flow rates, but unless you’re really monitoring everything closely, it’s easy to end up with stagnant spots that just make biofilm grow faster. Just my two cents from dealing with tenant complaints over the years...

Sometimes, over-handling can actually make things worse by disturbing settled gunk and spreading biofilm around.

That’s spot on. I’ve seen people get a little too enthusiastic with filter changes and end up with more headaches than they started with. Consistency is key - stick to a cleaning routine and don’t overcomplicate it. UV sterilization’s a solid call if you can budget for it, but even just keeping things predictable goes a long way. You’re definitely not alone fighting the biofilm battle... it’s just part of the territory with these systems.

I hear you about the filter changes - learned that lesson the hard way when I tried to “deep clean” my setup and ended up with cloudy water for a week. Sometimes less really is more. I’ve been eyeing those UV sterilizers, but my wallet keeps reminding me who’s boss. Has anyone tried using cheaper alternatives, like hydrogen peroxide or vinegar rinses, or do those just mess things up more? Not sure where to draw the line between “DIY fix” and “science experiment gone wrong…”

Not sure where to draw the line between “DIY fix” and “science experiment gone wrong…”

- Hydrogen peroxide can work in small doses, but it’s easy to overdo and nuke your beneficial bacteria. Vinegar’s even trickier - great for cleaning hardware, but I’d never run it through a live system.
- UV sterilizers are pricey upfront, but they’re set-and-forget compared to constant chemical tweaks.
- I’ve seen folks try pool shock or bleach in rainwater setups, but that’s risky unless you’re measuring everything precisely.

Curious if anyone’s had luck with slow sand filters or biofilters for greywater? Seems like a low-tech way to keep things clear without constant intervention.

Curious if anyone’s had luck with slow sand filters or biofilters for greywater?

Tried a DIY slow sand filter once in a rental’s laundry greywater - worked okay, but it clogged up way faster than I thought. Maintenance is no joke. UV’s pricey, but honestly less hassle for me in the long run.

Honestly, I’ve seen way too many folks underestimate how much gunk builds up in those sand filters. They sound simple, but you’re right - maintenance is a pain, especially if you’ve got lint and detergent in the mix. UV’s not cheap, but you’re trading upfront cost for less daily hassle. Ever looked into cartridge filters as a middle ground? They’re not perfect, but sometimes they hit that sweet spot between cost and upkeep. Curious if anyone’s tried combining a basic filter with UV for greywater - overkill, or actually worth it?

- Sand filters really are the “set it and forget it... until you can’t” option. I’ve pulled some out that looked like swamp monsters, no joke. Lint, hair, detergent scum - if it’s in your laundry, it’s in your filter.
- Cartridge filters are a decent compromise. They’re easier to swap out than backwashing a sand filter, but you still have to keep an eye on pressure drops or flow rates. If you’re running a lot of greywater through, expect to change them more often than the box says.
- UV after basic filtration? Not overkill if you’re worried about pathogens. The trick is making sure your pre-filtering is solid - UV doesn’t do much if the water’s cloudy. I’ve seen setups where folks skimped on the first stage and ended up with biofilm inside the UV chamber. That’s a pain to clean and kind of defeats the purpose.
- Cost-wise, yeah, UV isn’t cheap upfront, but bulbs last a while and maintenance is mostly just wiping down the sleeve every few months. Way less gross than digging out a sand filter.
- One thing people forget: if you’re using greywater for toilets or irrigation, you don’t always need drinking-water quality. Sometimes a cartridge plus a bit of chlorine dosing does the trick and saves you the UV hassle.
- Anecdote time - one client tried to run their shower greywater straight through a sand filter into their toilet cistern. Worked fine for six months, then everything slowed to a trickle. Turns out conditioner residue + lint = filter concrete.

Bottom line: there’s no perfect system, but combining basic filtration with UV isn’t nuts if you want peace of mind (or have kids who like to flush weird stuff). Just budget for more filter changes than you think, and don’t trust those “maintenance-free” claims on the box... they never pan out.

Yeah, totally agree about the “maintenance-free” claims - never seen one actually live up to that. I’ve noticed people underestimate how much hair and gunk ends up in those filters, especially if you’ve got long-haired folks in the house. And UV is great, but only if you keep up with the pre-filtering like you said. I’ve seen setups where folks skip a step and end up with a science experiment growing in their pipes. Not fun to clean out, trust me.

Maintenance-Free Is a Stretch, but Not Impossible

I get where you’re coming from, but I’ve actually had a bit of luck with some of the newer filter setups - at least compared to the older ones. They’re not truly “maintenance-free,” but if you set up a decent pre-filter and stick to a schedule, it’s not as much of a headache as folks make it out to be. That said, I’ve definitely pulled enough hairballs out of pipes to last me a lifetime... Maybe it just comes down to how much you trust your tenants to keep up with the basics.

I hear you on the pre-filters making life easier. I switched over to a dual-stage filter setup last year, and honestly, it’s been way less of a hassle than the old single filter I had before. Still, “maintenance-free” is wishful thinking - especially if you’ve got hard water or a lot of debris in your rain catch. I’m all for saving water (and money), but I do wonder if the city’s factoring in the long-term costs for folks who don’t have the time or patience to keep these systems running smoothly.

Has anyone actually crunched the numbers on what you save versus what you end up spending on replacement filters, cleaning supplies, and maybe even plumber visits? I’m not convinced it’s a net win unless you’re really on top of things. Curious if anyone’s seen a setup that truly pays for itself without turning into a weekend project every month...

Curious if anyone’s seen a setup that truly pays for itself without turning into a weekend project every month...

I hear you - maintenance-free is a unicorn, especially with rainwater and greywater setups. I’ve had my fair share of “quick fixes” that turned into full-blown Saturday sagas. Honestly, the filters alone can be a money pit if you’re not careful. Has anyone here tried those self-cleaning filter systems? I keep seeing ads, but I’m skeptical they’d survive a storm season (or my kids). Wondering if it’s just more snake oil or if there’s actually something out there that keeps things running without constant babysitting.

maintenance-free is a unicorn, especially with rainwater and greywater setups. I’ve had my fair share of “quick fixes” that turned into full-blown Saturday sagas.

That line about Saturday sagas hits home. I once thought I’d outsmart the system with a “set it and forget it” rainwater setup - ended up crawling under the deck every other month, cursing at a filter that kept clogging with maple seeds. The self-cleaning filters you mentioned? I’ve installed a couple for clients who were sold on the promise, but honestly, they’re not quite the magic bullet. They do cut down on the gunk, but after a heavy storm or two, you’re still dealing with buildup. And if you’ve got kids tossing who-knows-what in the yard, forget it.

One guy I worked for had this fancy stainless steel vortex filter - looked like something out of a sci-fi movie. It did a decent job for about six months, then he called me because water was backing up into his basement window well. Turns out, the “self-cleaning” part only works if you’re not dealing with leaves, pollen, and the occasional tennis ball. Ended up being more work than his old mesh screen.

I get why people want these systems to pay for themselves, but in my experience, there’s always some trade-off. Either you’re spending time or you’re spending money. The closest I’ve seen to low-maintenance is when folks keep things super simple - big first-flush diverter, oversized screens, and easy access for cleaning. Not glamorous, but at least you’re not tearing your hair out every time it rains.

Maybe someone’s cracked the code with newer tech, but I haven’t seen anything that truly lives up to the “maintenance-free” hype yet. If anyone’s got a setup that survived both storm season and a couple of wild kids, I’d be impressed... and maybe a little jealous.