Hose splitter leading to low pressure

Question

I recently added a garden hose splitter to my bib in my garage and outside, to be able to use 2 hoses at the same time from the same bib. I would sometimes need to run both my garage bib and outside bib at the same time, so there will potentially be 4 hoses running water simultaneously from 2 bibs. To give you a little context on my homes plumbing:

Main line coming into from the city is 3/4 inch copper. At some point, it changes to 3/4 inch PEX B, which feeds into the main lines of the home and hot water tank. All fixtures and hose bibs are 1/2 inch PEX.

Water pressure in my hoses was fine before adding the splitters, so I have a feeling the 1/2 inch PEX is not supplying enough water to keep pressure up in both hoses simultaneously. I would be able to run 3/4 inch PEX from the main lines to the hose bibs since they are located close to the 3/4 inch PEX main lines.

In your opinion, would increasing to 3/4 inch PEX help solve the low pressure issue? Would it be sufficient to run two hoses at full pressure simultaneously?

Thank you

Steven

Answer 1

Under no condition, and in no way, are you going to get multiple hoses running at 'full pressure.

Yes, absolutely run a 3/4 inch line from the main and make sure there are no places where the line gets smaller. Using the new type-A pex or old fashioned copper will keep a 3/4 inch inside diameter the entire way, while the older type-B crimp connections use fittings that go on the inside the of the pipe and reduce the diameter.

The bigger you can make the main feeder pipe, the better. But, if you wanna blow full blast out of multiple hoses, then you are going to have to step up to one inch all the way out to the curb and up-size your water meter too. Nothing is impossible, but some things are costly.

Be sure to up the size of the pipe between the meter and the splitter to 3/4 inch without restriction, or better yet, just step it up to 1 inch pex. It will help a lot. After you get that feeder pipe nice and fat, wait until your wife gets all warm and comfy in the shower with hair full of soap, quickly turn it on full blast.

Answer 2

There is a saying in mechanical engineering: pressure makes flow. The operating pressure from your city waterworks is essentially fixed. The pipe coming into your house has resistance, much like in an electrical circuit, creating a maximum amount of water that can flow through it per second, and pretty much nothing downstream of that constriction can do anything but slow it down.

You have a 3/4" line coming into your house, feeding 2 1/2" hoses. That is working OK, because 1/2 pipe is about half the area of a 3/4" pipe.

But if you double the amount of hoses you want to supply, you're now trying to provide double the amount of water per second. Your problem isn't pressure it's flow. The pipe from the meter just can't provide enough water to keep all four hoses running at what you are used to as being full-blast.

Increasing all the lines to 3/4 will give you a very slight increase as you'll have reduced line losses, not enough to matter though. You would increase the amount a single hose can deliver exclusively, but you'll still be limited by what your city supply provides.

If you were to increase your supply line to 1", you'd have about 4x the area of the half inch piping going to the hoses. You'd be able to supply them at full blast then. Going even larger would allow even more water. However, the bill from the city to do so is probably going to be steep.

Answer 3

You may consider rummaging in the basement/utility room/wherever to see where your water comes in from the main. Many houses have a pressure reducing valve (PRV) to lower the incoming water pressure before it's used elsewhere in the house.

If that's the case, you may be able to tap into the main feed for the house before the PRV, thus providing full city water pressure to the hose bibs. You'd probably want larger feed lines out to the garage to maintain the higher pressure and flow rate.

You'd still want the rest of the house on the low-pressure side of the PRV because you don't want to cause any issues there.

Answer 4

Thank you for all your answers. I experimented with different hose sizes and I pretty much came to the conclusion that low flow was the source of the problem, as whatsisname mentioned. Coverage was better with my sprinklers when I used a larger hose than when I used a smaller one, independent of pipe size.

I ended up increasing one line to one hose spigot to 3/4" and I left the other spigot on 1/2". I have to say that so far, I'm pleased with the results of the 3/4" spigot. I can water my entire lawn without having to move the sprinkler around. However, the trade off is that flow on my 1/2" spigot drops quite a bit when I run the 3/4" spigot at the same time.

As many have mentioned here, I think the only way to be able to run all 4 hoses simultaneously would be to increase the city main into the home, and the problem isn't worth that much effort haha.

Thank you all for your input and I'm glad I found this forum! I'll definitely be back here to discuss future issues