Soda Bottle to GHT (Garden Hose Thread) Modification

A soda bottle cap easily fits the male end of a garden hose. But the soda bottle won't fit the female end. Soda bottle threads and garden hose threads are similar but not identical.

Soda bottle threads can be easily modified to fit garden hose threads.

By "soda bottle" I mean one- and two-liter bottles that Coke comes in, and Pepsi, and even Schweppes.

By "garden hose threads" I mean the US standard, not the British standard.

Get a cup of hot water, as hot as you'd make it for instant coffee. Dip the soda bottle threads in the hot water for 15 or 20 little alligators, then take it out and screw on a garden hose fitting. Done.


Myself, I'm not a practical person. I'm the kind of person who needs step-by-step instructions, plus hints and tips. But I don't have much of a memory. I make notes on how to do things and what tools to use, and then usually misplace the notes.

I wrote the instructions below originally for my own use, to develop a reliable process, because I want to make a 20-gallon water pressure tank and I'll need to modify a lot of two-liter soda bottles to do it.

Preparing a Bottle

1. Finish the soda. Rinse and save the bottle. Save the cap, too, as it will fit on a garden hose.

2. Cut off the plastic band that once held the cap on the bottle. For this I use my wire cutters -- diagonal-cutting pliers, I guess they're called.

As the Educational Innovations site says, make sure you don't scratch the bottle. A scratch is a weak point, and if you put air or water under pressure in a scratched soda bottle, the bottle may fail: KA-BOOM! Just be careful.

2b. You'll want to take the label off too. It makes your project look so much nicer! Chris Notap says use WD40 to get the glue off the bottle. Works great.

Again, safety: A comment on Notap's video says repeated pressurization and depressurization will weaken the soda bottle, and it will eventually explode. Notap agrees. Maybe this ought to be a conceptual project, not one that actually gets built. Maybe I'll make a cage of hardware cloth for my pressure tank. The safest thing would be not to use soda bottles in pressure applications.

On the other hand, seeing is believing.

3. To modify the threads I use a brass hose nozzle like the "bonus" nozzle shown here, the short one. Brass is good because it is less willing to change shape than the bottle.

The threaded end of my bonus fitting is full of threads. Some fittings don't have much thread at all. More is better.

My bonus fitting is one piece, not a swivel fitting.

3b. If your bonus fitting end has a hose washer in it -- it probably does -- take the washer out. It will get in the way when you are modifying the soda bottle threads. A small screwdriver or an awl will dig the washer out.

4. Start screwing the bonus fitting onto the soda bottle. Take your time with this!!! It will bind almost immediately when you put it on. Don't force it. What's important is to make sure the fitting will go on straight. If it goes on crooked you may ruin the bottle, or the bottle connection may leak, or the bottle may connect at an angle and look funny and your friends will laugh at you.

The threads don't match, so the nozzle wants to go on crooked. Don't let it! Just keep trying till it looks right, then screw it on. Sometimes I do it half a dozen times so I can see what looks good and what doesn't. It won't go on far. Don't force it. Just get it started.

5. Make sure you have your bonus fitting started square on the bottle, not at an angle. Do it over if you're not sure. And only get it started.

6. Get pliers or a wrench or something you can use to tighten the fitting on the bottle. Don't tighten it yet.

7. Put hot water in a coffee cup. Hot like you are making instant coffee. Fill the cup pretty full. The hot water will soften the plastic of the soda bottle enough that tightening the bonus fitting will modify the threads of the bottle. Don't tighten it yet.

8. Make sure you can dip the bottle into the hot water enough to just submerge the bonus fitting. You want the whole fitting in the hot water, and down maybe 1/4" below the surface.

9. With the nozzle in place, hold the bottle in the hot water for 10 or 20 seconds. Then pull it out and tighten the fitting. Take all that you can get easily. Don't force it.

Let me be clear: Push the bottle and your bonus fitting together with some force. But don't force the turning that modifies the threads.

When I did this last year I dipped for 10 seconds, and I could only get a quarter-turn at most. Doing it the other day I dipped for 20 seconds, and the nozzle went all the way on after just one dip. A few seconds extra in the hot water bath seems to make a big difference. Either that or the fussiness about getting the bonus fitting on good and straight really paid off.

If you need to dip more than twice, get new hot water.

When you get the fitting all the way on the bottle, I suggest leaving it on for a few minutes, until the assembly has cooled.

If you test your re-threaded bottle under pressure, be sure you have a way to de-pressurize the thing without hurting yourself. For example, connect a tee fitting (with shutoff valves) to your hose, and screw the bottle into one leg of the tee. You can open the shutoff on the other leg to release the pressure.

Oh -- pressure. I'm only working with 60 or 65 psi max, water pressure. I don't think I'd use soda bottles at higher pressures.