They use these with cattle and horses. My grandfather would check them, and if the water was green it was broken.

Posted at 7:05 pm on Jul 4th, 2008 by Jinto Lin

my cats are scared of these things, we once had a commercial one and only one cat would drink from it

Posted at 7:12 pm on Jul 4th, 2008 by biojae

It’s a good idea, but float switches fail. What’s really needed is a small microcontroller that determines the water has been flowing for too long and does a hard shutdown.

Ideally, I’d use two solenoids in series for redundancy, and a current sensor for determining the the duration the solenoid has been open. A flow meter would be even better, but more expensive. Then you can determine a failure prior to the first solenoid.

If the water has been flowing too long, you shut down the solenoids, and if you continue to detect flow, you turn on an alarm.

Or, since no device or program is complete until it can send email, send an SMS to your cellphone or crackberry.

Posted at 8:01 pm on Jul 4th, 2008 by jc

I was just thinking about what biojae (#2) said. Seems like adding a PIR motion sensor so that it would only fill when there was nothing in front of it would help.

Conversely, one could pretty much assume that it will refill more often due to drinking rather than evaporation, so add a 2 minute timer between the float switch triggering a low water condition, and refilling.

Posted at 8:14 pm on Jul 4th, 2008 by jc

i don’t know if you guys have taken apart toilets but what lets water into the tank is called a ballcock. they are a solid mechanical device that lasts for years. if overflow is a concern, this is something that could easily be piped to a condesate pump, basement etc. i think this is the easiest way about it and has no electricity plus water hazard

Posted at 9:30 pm on Jul 4th, 2008 by ocman

Another Potential method would be to use Capacitive based sensors, they use them on air planes and other objects to determine how much fluid is within a container without having to come into direct contact with the fluid, use that sensor with a microcontroller and you would be able to actually see how much water is in the dish and control a solenoid from there.

Posted at 9:35 pm on Jul 4th, 2008 by chubs1646

Needs a couple of mods.

First, there should be two tanks of water, at the same level, connected with a tube. This will allow you to fill the secondary one while keeping it a few feet away, and protected in a box to prevent the float being displaced or the animal being frightened. A small second float switch set a bit higher could easily cut off the flow if the first ended up stuck open.

Second, another tube off the drinking bowl should go to pump (a fish tank pump would work) also stored in the hidden box. Periodically (once per day?) the pump should engage (a cheap timer switch would do) for long enough to empty the contents of the drinking bowl — changing the water.

Posted at 10:12 pm on Jul 4th, 2008 by Andrew Pollack

@jc Couldn’t you also use a weight sensor at the bottom of the Tupperware container? I mean you’d just set the weight of full to the switch for the the pump. If water is lost, weight is lost. You could also add this as a redundancy to the float switch should the float switch fail.

Posted at 10:42 pm on Jul 4th, 2008 by BlizzardDemon

This is very similar to a fish tank auto top off unit. Just google auto-topoff and you will find a million builds that are virtually identical. Cool though.

Posted at 11:18 pm on Jul 4th, 2008 by buddy

if you were crazy, or did not really like your pets, you could rig a hard shutoff (to keep from flooding the house) by putting a hot wire and a ground wire (shielded from the pets’ curious appendages) so if the water reached the top of the container, it would bridge the hot and ground, which would promptly pop the gfci.

but a microcontroller timers and capacitance sensors are probably safer.

Posted at 1:56 am on Jul 5th, 2008 by Joey Y

> the float switch

my cat would just sit on it

Posted at 7:29 am on Jul 5th, 2008 by rasz

A dehumidifier as water source would be even more hacktastic.

Posted at 11:01 am on Jul 5th, 2008 by jk

this is ridiculous. first of all, the entire aparatus can be replaced with an entirely passive system due to a property of gravity and pressure.

the real problem lies in the fact that when your animal drinks, the bacteria from their mouth is left in the water. if you keep adding water and never replace it, the bacteria stays and grows. take a few minutes and leave fresh water for your animal!

Posted at 11:57 am on Jul 5th, 2008 by siokaos

well, this is interesting, but heres how i would improve it:

use a tube to fill the tub from the bottom, rather than pouring it in from the top, possibly with a diffuser over the end of the tube, to minimize the sound and motion that might scare a cat away

If you do that, restrict the flow to something extremely low, to further reduce the disturbance in the water. your cat likely will not be drinking large amounts of water quickly, so you don’t need a huge inrush of water to fill it back up.

That should sufficiently reduce the cat scaring qualities of the thing.

As far as all the other stuff about making it double-redundant etc, that seems like overkill. Just use a Normally closed valve and a robust sensor and i think you’d be fine, though you may want to put this in a place where overflow will cause the least amount of damage, just in case.

-Taylor

Posted at 2:35 pm on Jul 5th, 2008 by Taylor Alexander

Okay, so, as stated above, a ballcock would make a LOT more sense

Add a UV light to kill bacteria…tada, safe

the automated empty/fill pump is a good idea.

Posted at 4:03 pm on Jul 5th, 2008 by Frollard

Oh snap, that would be a REALLY BAD THING if the dumb animal knocked the bowl out from under it. It’d flood your house.

Posted at 7:22 pm on Jul 5th, 2008 by Widdershins

Decent DIY advice for the uninformed.

Just one thought… pets eat poop and drink urine… do we really need to change their water?

Posted at 10:48 pm on Jul 5th, 2008 by Louis II

Clearly it needs a GSM addon, so it can SMS you when it breaks. You’re a thousand miles away on vacation, so you can’t do anything about it, but you at least know you’re screwed =-)

Seriously, though, agree about putting the inlet below the water line (most pets hate surprises!) and switching to at least a solid-state sensor, if not a mechanical control/ballcock. Maybe if you’re going to have it be microcontroller-based anyway, you could set up an automated nightly “flush” system, and have a computer-controlled outlet valve that runs to a drain somewhere? Open the drain, wait a few minutes, close it, run the water till it fills, open the drain, wait, close it, and refill. Guaranteed fresh water daily. Shouldn’t even be hard/expensive to add the extra kit, though I guess people have a spare fresh-water hookup in more places than they have a spare sewage/drain line.

Posted at 12:15 pm on Jul 7th, 2008 by James

I think the idea here was to have running water for very picky pets, particularly cats. Something in their genes I guess, about the fact that running water is generally more healthy. Most of cats I know will prefer to drink from a dropping tap or a fresh puddle that in their bowl.

Posted at 2:02 pm on Jul 7th, 2008 by Magma

I agree with siokaos, the whole is unnecessary. Just place a large shallow reservoir of water in another room, and connect it to the pet’s dish via a small hose. Arrange it so that the large reservoir’s water level is the same as the pet dishes. As the pet drinks, hydrostatic pressure will force water from the reservoir into the dish until the levels are equal. If the reservoir has M times the volume of the dish, the dish water level will fall M times slower than it would normally.

In essence, it’s like connecting a small capacitor in parallel to a large one. The small tube is one wire, the atmospheric pressure serves as the “ground” in the electrical case. As the small cap drains, it is continually replenished by the large one. Or, the capacitance is the sum of both capacitors.

Posted at 2:36 pm on Jul 7th, 2008 by Hasan Murtaza

@20
That’s just stupid. The whole point is to have it connected to the plumbing so you don’t have to worry about it (provided you pay your water bill). I wouldn’t use it, but that’s because my cat will just drink from the toilet.

Posted at 4:07 pm on Jul 10th, 2008 by Spadefinger