Occasional Very law water pressure in the mains

It will be difficult to find a simple pump, tank, and pressure switch setup that will operate consistently over the range of inlet conditions that you are experiencing. Water supply (amount of water) and pressure are absolutely linked. The supply may be in the main but it can't be extracted through the 1" pipe because there is not enough pressure in the main.

You can extract more but not enough water from the pipe by reducing the pressure at the outlet end with a pump. However, that pump cannot then deliver the pressure required to shut off the pressure switch.

The cistern provides a stable condition that can be the basis for selecting a pump, pressure tank, and pressure switch system. The cistern pressure is always atmospheric pressure and there is always a supply, up to the limits of the cistern and the ability of the service to keep it full at low flow rates.

1. Decide what pressure range you want.
2. Decide what GPM you want for steady state (long shower) conditions.
3. Determine total gallons for peak 10 minute period and peak 1 hour period.
4. Determine what supply flow will be used for the system.

That will be the design point for selection of the pump, cistern, pressure tank, and pressure switch settings to deliver what you want.

A shallow well jet pump will also deliver much more flow at lower pressures if demanded. The only limit will be the storage in the cistern and the delivery rate from the utility.

Bob1000 said:

I was trying to avoid the cistern concept but it seem that it would be the best thig in my case!

Any comments?

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Try/trying = failure....

First I'll say I appreciate your follow up, thanks but.... you should have followed the previous advice about using an atmospheric storage tank, submersible pump controlled with float switches, a CSV with a small pressure tank because...

The cistern and CSV is your only choice to meet the requirements you have and the service satisfaction you want.

Can I also use a cistern in the system parallel to the city pipe in the same time , and the pump would suck from both sources in the same time ?
The idea is that I want to use a small cistern which would help in the noon time of peak demand but worrid if it would be enough for a shower
I am thinking of using a 250 liter one and put it in the pump room
Any comments?

Sorry BobNH

Sorry Bob NH , I posted my last question before I realize that you have replied to my question about the cistern concept because i was in page 2 ....long one now ...thank you all for bearing with me...., now I would need a 250 to 500 liter cistern (depends on the shape as I have limited space in the pump room) and also depens on if I can use it parallel to the city line in the same time if there is a way in working out the piping.
In that case , my existing pump , pressure tank and pressure switch will be fine al what i would need to add more is a float switch for the cistern and an electrcal float switch for the pump
comments please
Thank you all

What will you do for low flow times from the city line when you need more water from the storage tank and you've not resupplied the tank from the city flow, and the city flow is too small?

I think I'm right when I said/say; The cistern and CSV is your only choice to meet the requirements you have and the service satisfaction you want. And if you don't have the required space for the tank etc., then your only choice is to make more room or to use less water.

Bob1000 said:

comments please
Thank you all

Click to expand...

Bob1000, Check your Private Messages.