# Decrease in water pressure



## AAP (Oct 15, 2015)

My customer recently purchased a duplex the 3/4" Watermain was reduced to half inch and then split to supply each apartment with half-inch cold water supply. When running water ther is plenty of pressure. Turn on another fixture and the water drops to a trickle. I re piped the Watermain so the cold to each apartment with a 3/4" X 3/4" X 1/2" T. The problem persists and there is plenty of water pressure to supply more than one fixture but still the problem persists after the Repipe. Any suggestions? Thank you


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## rwh (Dec 17, 2014)

Try a booster pump


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## Tommy plumber (Feb 19, 2010)

*Hello! Introduction Requested* 
An intro is requested from all new members. In case you missed it, here is the link. http://www.plumbingzone.com/f3/. 

The PZ is for Plumbing Professionals ( those engaged in the plumbing profession) 

Post an intro and tell our members where you are from, yrs in the trade, and your area(s) of expertise in the plumbing field. 

This info helps members who are waiting to welcome you to the best plumbing site there is. 

We look forward to your valuable input.


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## Flyout95 (Apr 13, 2012)

Way undersized. Need a new main service or a booster with holding tank.


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## srloren (Nov 19, 2014)

Flyout95 said:


> Way undersized. Need a new main service or a booster with holding tank.


Agree. New main required. Without knowing the current pressure and distance from the meter I can only suggest a 1" main tee off with 3/4" to each unit. Ideally you should have 3/4" to the water heater and may others depending on the layout, pressure, distance etc.


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## plumbdrum (Nov 30, 2013)

First off do an intro, second. You are a Ma plumber, you should know the answer.


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## 89plumbum (May 14, 2011)

AAP said:


> My customer recently purchased a duplex the 3/4" Watermain was reduced to half inch and then split to supply each apartment with half-inch cold water supply. When running water ther is plenty of pressure. Turn on another fixture and the water drops to a trickle. I re piped the Watermain so the cold to each apartment with a 3/4" X 3/4" X 1/2" T. The problem persists and there is plenty of water pressure to supply more than one fixture but still the problem persists after the Repipe. Any suggestions? Thank you


Just curious, what do you call 'plenty of water pressure'?


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## bct p&h (Jan 19, 2013)

I actually sized out the water main using minimum required fixtures in MA and decided to hold off on posting it until you do an intro. I find it hard to believe someone could pass the MA journeyman exam and not know how to size water pipe in a duplex.


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## plumbdrum (Nov 30, 2013)

bct p&h said:


> I actually sized out the water main using minimum required fixtures in MA and decided to hold off on posting it until you do an intro. I find it hard to believe someone could pass the MA journeyman exam and not know how to size water pipe in a duplex.


Exactly. Sounds like a handyman to me. I hope he's not in my area


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## bct p&h (Jan 19, 2013)

plumbdrum said:


> Exactly. Sounds like a handyman to me. I hope he's not in my area


I hope he is in your area haha


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## Redwood (Sep 8, 2008)

rwh said:


> Try a booster pump


I agree! A Godwin CD-150 would be a perfect pump for this application...


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## plumbdrum (Nov 30, 2013)

Somebody didn't pay attention in their tier 3 and tier 4 classes.


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## chonkie (Jul 31, 2014)

1/2" main supply is fine. You need a PRV at the first unit so the remaining water pressure goes to the other unit.


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## AAP (Oct 15, 2015)

so what you are saying is 2 fixture units is too much for a 1/2" cold water supply, and you are insulting my intelligence. Very welcoming thanks for nothing


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## AAP (Oct 15, 2015)

Chonkie and redwood Thank you


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