Leaking xp7240 clean valve

There are many places for the water to leak out the bottom on those. You are going to need to remove the covers and have a look. Is the water clean or is it part of your brew? In order of most likely to least likely
1) Barista seal at bottom of brew chamber
2) Distributor
3) Tank seal
4) Tamping piston seals
5) Flexible hose or connection
6) Hydraulic Ram
7) Relief valve on end of pump
You are not going to figure it out with the covers on and you will have great difficulty running it with covers off to be certain where it is coming from but that is what most of those issues is going to require.

Replace that pressure valve and also inspect it for leaks from directly under the boiler, from that pressure valve and from the top of the hydraulic ram. If when you buy your valve you find the white housing will not fit where the old one came from you can just use the piston into your old housing. Check this before removing the hose clip from your old piston housing. If your old piston housing is leaking badly before you even do this job then you will need to replace the whole distributor as sometimes a piston housing retaining lug can fracture, there are 3 of them and they are part of the distributor.

The problem that you describe is more likely the check valve. Follow the air discharge tube from the pump to the tank. The brass or aluminum fitting at the tank is the checkvalve. Clean debris in valve or replace valve with generic. Should cost about 20 dollars. Make sure that the air discharge tube is clean of carbon deposits so that the new valve will fail. Good luck

Leak at pressure switch is an indication that the in-tank check valve is leaking.
Follow small hose from pressure switch to the tank (usually brass valve). Remove hose at the brass valve and check for leak there. If leaking replace valve with generic valve from ebay or WWw. grainger.com or use exact part (some valves can be cleaned, as debris can be lodged between seat). Good luck

it is a common issue. See the posts for xp7240. The seal within the plunger is worn or dirty or the valve is sticky. Posted both instructions on other posts.

My XP7240 has the same problem. I went through all cleaning cycles and the filter in the boiler still gets clogged up with coffee oils. This causes back pressure and blows the boiler seal out. Easy replacement if you can turn a screw driver.
Part number for Seal: MS-5015004. You might as well change the Jack too. (the part that slides into the boiler that compresses the ground coffee. (this is a redesigned double seal unit) Part Number MS-0697072.
Both these parts you can get at http://www.krups.com/Tools/Contact/Contact.htm choose your country and email the parts list. Mine cost in Australia $27.00 including shipping.
Good luck.

See post on leaking xp7240. It is almost the same machine. This post explains how to fix it (valve is blocked but can be easily cleaned)

It is probably blocked or dirty inside. Try cleaning tablets other wise see the other posts for cleaning the pressure valve inside the machine.

Yes, you're machine is identical to the xp7240. Look up the post on leaking xp7240 and follow the instructions on how to open the machine and fix the valve.

You need to open the machine which is easy see my other post on leaking krups xp7240. The grinder can be taken out by removing two torix screws. Probably the electical brushes are gone. Take the grinder engine to a repair shop where they replace them.