Python Water Changer Won't Fit Your Faucet? Try This First
The hose that drains and refills your tank from the sink screws onto nothing in the house. There's an order to try things in, and step one is free.
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Late in 2025 somebody in r/Aquariums posted a plain piece of advice: if you don't have a Python, get one. Then one owner put a damper on it.
I have one and realized that literally none of my faucets are compatible with any of the available adaptors. Yes I've taken the aerators off, even damaged a faucet trying to make it fit. But otherwise, yes this is the way and I still make use of it with a water pump and bathtub.
u/Medical-Weekend-116, in r/Aquariums
Spend an afternoon there and this is the water changer complaint that keeps coming back. What you buy depends on what's under your aerator, for a Python or any of the hoses like it.
What kind of faucet adapter do I need?
Unscrew the aerator before you buy anything. That's the little mesh cap on the tip of the spout. The maker's own FAQ says to start there.
With it off, you'll find either a female thread inside the spout or a male thread on the outside. The brass adapter in the box does both. For a male thread you take out its large white washer.
The same FAQ calls a non-fit rare, but sells two more adapters for newer faucets with smaller threads. The thread above suggests "rare" is doing a lot of work.
Two people in the 2025 thread add a tip each. On most gooseneck spouts, a little piece unscrews and the adapter goes in there. On a faucet with a sprayer, the spray head itself screws off, and a lot can attach to what's left.
Under the aerator you'll find one of four things:
- A thread the brass adapter screws onto. You're done, and you can stop reading.
- A thread, but small and fine, often plastic, inside a pull-down spray head. You're hunting for an adapter, probably at a hardware store.
- No thread at all, just a smooth round spout. A rubber sleeve goes over it, and that's the next section.
- Nothing you'd trust a hose on. The shower, the tub or a pump.
A smooth spout with no thread: the slip-on rubber sleeve
The Python Universal Adapter is a grey rubber sleeve with a hose clamp around it and a threaded end sticking out. It goes over the spout, the clamp goes tight, and the water changer screws onto the other end. The tap needs no thread at all.
Someone whose new Glacier Bay faucet had beaten the brass adapter was pointed at exactly that part, and it worked on theirs.
In the 2025 thread a UK owner with a threadless kitchen tap did the same with a silicone push-on adapter that tightens with a metal collar. Annoying to buy another part, they said, but cheap and worth it.
A third owner slips a silicone sleeve sold for RV water hoses over their faucets and holds it on with zip ties, because it slides off otherwise. Still better, they say, than pouring buckets or duct-taping the hose to the tap.
The clamp matters more than it looks. In another thread, someone got their adapter onto the faucet and found it fell off when they turned the pressure up. The fix was a few turns of Teflon tape on the faucet, plus the clamp, because over time the hose lets go more easily.
Python adapter for a pull-down faucet
Pull-down and pull-out sprayers come up again and again in these threads, and the fix for them is a hunt rather than one part.
One commenter's rule of thumb is that a pull-out faucet usually wants a dishwasher aerator adapter, 55/64 inch by 27. The 15/16 inch by 27 size, they say, is the older kind of faucet the Python was built for.
The person who started a thread on pull-down faucets found their Delta's aerator took an M16.5 thread, which very few adapters are made for. They needed two in a row: one from M16.5 to 55/64, then a second from 55/64 up to the 3/4 inch thread the Python takes.
So take the Python's own end to a hardware store that keeps fittings in little drawers, as one owner advises, and try things against it. A multipack from the store or a bag of mixed adapters online gets you there by elimination.
Even when the adapter fits, a modern faucet can be too slow to drain the tank. The Python's tap end is a little pump with no motor. Set to drain, it sends the tap water rushing down the sink, and the rush sucks the tank water up the hose and down the drain with it, like a drink up a straw. The sink needs to be lower than the tank, the more so with a slow faucet. The Delta owner's faucet pours at about a gallon a minute and their Python still drains the tank, which they put down to a tall tank stand and a short hose run. Someone who tried two kitchen faucets and couldn't pull a siphon from either runs theirs off a bathroom tap instead.
Nothing in the kitchen fits: the shower, the tub or a utility sink
Give up on the kitchen before you give up on the hose. An owner in an old house connects theirs to the handheld shower head through a plumbing adapter. Another runs it from the shower with a diverter and a shower hose.
A third feeds a fifty-foot changer down the laundry chute to the basement, home to the only tap in the house with threads and the only tub big enough. An owner whose new Moen faucet refused even a 3D-printed adapter runs theirs out the door to the garden hose, which they hate.
Still nothing? Skip the faucet
The owner who opened this piece, the one with the damaged faucet, still uses their Python, with a water pump and the bathtub.
A reply to the Delta owner puts it more bluntly. A pond pump and a length of vinyl tubing do the same job, with no faucet involved and no water run down the drain to start a siphon. The hose drains the tank into the tub, and a pump in a bucket of fresh water refills it.
Start at the sink tonight. Unscrew the aerator and look. Whatever's under it picks the part for you, and if there's no thread, the Python Universal Adapter is the one to order.
