Leaks even with the o-rings in place.
598762
The cap does not seem to seat down far enough into the bottle to make a solid seal. It would leak when turned upside down and shaken. Not reliable enough.
803894
I put the first filter in service and it started leaking with in the first hour . I removed it and checked the o ring and they appeared to be in good condition. I put a small amount of petroleum jelly on the o rings and reinstalled the unit. Next morning there was a puddle of water in front of the fridge.
  At the point I installed the second filter and it is doing fine. I would not recommend this filter.
2186110
The bottom part connected to the hose keeps leaking no matter how tight I make it. I even changed out the rubber ring but it still leaks.
1789782
I have 1.5" and 2" piping. The large O-ring is just a bit too large, when I put the jandy cover back on, the large O-ring comes out, leaving an unsealed valve.

These DO NOT FIT. DO NOT BUY.
3140241
These work OK for rabbits, but after about one year of use they started to leak badly.  Trying to adjust them works sometimes, but several of them just could not be adjusted since they leaked no matter the adjustment.  It would be nice if the seller included some o rings so that they could be swapped out once a year.
406384
Ford 2004 Explorer Sport Trac.  Like all the other comments.  The O-ring is too big!  Didn't make it to the auto store as there're closed.  Luckily I have 1200 grain sandpaper, cordless drill, and a drill bit to place o-ring on.  Long story short, sanded it down to make it work.  Only time will tell if it's good enough.  No leaks so far!  What a pain in the arse! Vendor should provide extra o-rings for us DYI mechanics.  Lol!
871324
Cooler itself seems ok ,only time will tell. However the gasket kit that comes with this is absolute trash. The top part of my oil cooler housing leaked due to poor o rings, I had to take everything back apart and spent $75 on the Ford gasket kit. Now there are no leaks. Once you feel the gasket and O rings side by side you can really tell how bad they are
1066177
The o-ring that comes with the filter is much too large for it, but the filter will not be usable without an o-ring. It leaks pretty badly when not properly sealed. Luckily, I had a spare, smaller, o-ring lying around and everything worked out just fine. Nothing leaks and the water tastes fine. I'd definitely buy it again, even knowing that I have to supply my own o-ring. It beats paying the retail price.

Update: It started leaking about 2-3 weeks in and wouldn't stop, no matter what was done to it. I just decided to buy one of the legit ones from the manufacturer. More expensive, but they don't ruin everything with water.
751761
The rubber O-ring in the gate valve leaks from the first time I used it tried to change the O ring but that found out the gate was not flat and would not create a good seal
1520576
Difficult fit, so needed special tape for a sealer.  Still leaks.
137443
Broken with in 1.5 years. Started leaking from the back of the unit. I believe the rubber o-ring is the culprit.
3099500
I ordered several of these last year and liked them fine at first.  These are the new design that uses an internal O-ring instead of the sealing washer.  It wasn't long before the O-rings tore and the connectors became unusable.  I posted a question on Amazon, asking if anyone knew of a replacement O-ring, but the answers received referred to the sealing washers, not the O-rings.  I bought four possible sizes from the local hardware store but none worked.  Realizing that the products are made in China, it was not unreasonable to think the O-rings might be metric.  EBay was the source for a bag of Buna-N 70 metric O-rings, 20mm OD x 16mm ID for much less than the four purchased locally.  I installed them, used a bit of silicone lube on the mating parts, and they worked perfectly, withstanding repeated connections this summer.  The fittings snap together properly and so far there have been no O-rings coming out of the fittings when the hoses were drained, but even if they do, there are plenty more on hand.  With this knowledge, the fittings are great because they are the only ones I've tried that are truly leak-free with 100 PSI water.
716442
The O ring is useless, the cap is too small for the O ring to make contact with the fill tube.
4810766
With the included rubber washer, mine leaked where it screws onto the pipe out of the wall, no matter how tight I cranked it on.  Simply replace the included rubber washer with a 3/4" outer diameter, 1/16" thick O-ring from the "Plumbing" isle at your favorite home-improvement store - a couple bucks for a 10-pack box.  Gently ensure it's uniformly seated inside with small flat screwdriver or whatever, then tighten only until it stops leaking, as it's easy to crush the O-ring even with what might seem like a normal degree of tightening, even with just your hands.
4655615
The containers leak so the water gets pretty gross, and they're WAY too large even for XL eggs. They work better if you add 1.5 eggs to each container.
3638192
After replacing the filter, the shower-head now leaks and sprayed water all over. It didn't come with any O rings., now we have to get a new shower head.
4413291
Make sure you really tighten the top as even a slightly loosened top will cause a small leak. Maybe some from of o-ring could improve this.