My cold taps and loo cisterns upstairs are fed from a cold water tank in the loft. I'd like to do away with the tank and simply connect everything direct to the main. Is there any danger that the higher pressure could cause leaky joints in the pipework that is now 40 years old.

What is pressure on main line?
What size is main pipe?
What kind of pipe?

Instead of starting another question why not add facts to this thread by answering a few questions that are very important.

Is that thank pressurized or is it a holding tank that sends water to the pipes below by gravity ?

Also, is there a Pressure Regulator installed on your main line ?

Back to you

Milo

Many thanks for your responses.

I don't know what the pressure on the main line is, but the house is at 1000 ft elevation and the water comes in by a 22mm alkathene pipe. The pressure was sometimes so low that my electric shower would not start but gave a low pressure warning so I installed a shower power booster. The cold tank is not pressurised - just a holding tank. There is no pressure regulator on the main line. Note that all the downstairs cold supply - taps, loo, washing machine - are plumbed directly to the main.

talaniman - Apologies for the re-post I could not see my original post so put it in again.

No, you cannot do away with your holding tank. Not because of the pressure on your pipes but because you would, at times, be with out water to the upper floor.

The reason you have the holding tank is because at times the pressure and flow of the municipal water supply is insufficient to reach second floor. Let us say that you and all of your neighbors decide to take a shower at the same time each morning. The municipal system just doesn't have enough pressure and volume to meet that need. There just isn't enough water to go around.

So you install a holding tank in the attic. During times of low use the tank is filled for your use during times of high use.

You could remove the holding tank and install a booster pump on the main line but I suspect that is not permitted. To do so would probably interrupt the water supply to other consumers on system.

Check with authorities, you may be able to large holding tank somewhere outside and then pump from the holding tank to your house. This would allow you to determine you own water pressure.

This would in effect be a well system. Only difference would be that the water is coming from the municipal system, rather than from the ground.

Thanks hkstroud but my situation isn't quite like that. Firstly, I live in a remote rural location and have no neighbours. Secondly, as far as I am aware, there has never been a situation where there is no water flow to my holding tank in the loft - whenever some water is used from an upstairs tap the tank immediately starts filling up again.

OK, then check to see is you have water (enough water) at the upper floor when water is being used at the lower floor.

If you have sufficient water flow and pressure at both the upper and lower floors simultaneously then you could eliminate the holding tank.

PS
There would be no increased pressure on the pipes.

If you are interested and it is permitted booster pumps are available.
https://www.youtube.com/watch?v=VJS4eO4GF40