Improving water pressure

Our house has poor water pressure, not terrible but if you're in the shower and someone turns on a tap you're in trouble.

We want to add at least one other shower and sink etc but I am concerned that the pressure is going to be a real pain and definitely couldn't handle two showers at once.

All cold feeds come straight from the mains (there's no tank) and the hot again comes direct via a Vaillant boiler with no tank.

There is a very old redundant water tank in the loft - completely disconnected.

What are my options to improve pressure for the shower(s)? I guessed I could reinstate a cold water tank but would that make much difference as it would be refilling during a shower and therefore taking pressure away from the boiler and hot feed?

Is the problem with both hot and cold, or just with the hot? If it's hot and cold you could be suffering from an undersized water main. What size pipe is it going to your stopcock?

If it's just the hot you're having trouble with then you're almost certainly just maxing out your boiler, which has a flow restrictor fitted to limit the flow through it (too much flow and it simply wouldn't keep up, so you wouldn't get hot water).

Either way, you won't be able to have two or more showers running simultaneously off your boiler, which is a combi boiler, as it simply won't keep up. This is true of almost all combi's on the market. You'll need a hot water cylinder of some sort, and in your situation I'd say probably an open-vented one with a pump pumping both hot and cold water to your showers. This will mean re-instating the loft tank, and there will be a bit of fiddling about with the pipework to do. It is possible, although not usual, to heat a hot water cylinder off the heating circuit of a combi, so you wouldn't need a new boiler, but it's still not going to be particularly cheap to do.

Not much choice really as it sounds like youre on a combi.

Best thing to do would be to check exactly what pressure you do have and go from there, your water supplier is obliged to give you a minimum pressure

It is both hot and cold that have poor pressure. The rising main is a 22 I believe.

To give you an example, I plugged a sprinkler into the outside tap which is just by the rising main, and it barely covers half the surface area it's supposed to.

I took a photo of the water meter, does anything on here indicate pressure?

There's no indication of pressure on a water meter. The static pressure could be fine, but the dynamic pressure could drop rapidly as the flow rate increases.

Check all stop taps (internal and external) are fully opened.

Time how long it takes to fill a bucket of known capacity from your kitchen cold or outside tap. That doesn't indicate pressure, but it should give an indication of the maximum flow rate you have available.
Most would expect a flow of the order of 20 Litres per minute or more, that would normally fill a 2 gallon bucket in about 25 seconds.