All condensing boilers release a slightly acidic condense liquid. By law, this liquid has to be neutralized before being released into the local water course. The best way to do this is to install a Condense soak away outside.
All they are is a small cylinder with holes at the bottom and lime chippings inside. Bury them in the ground and run your condense pipe from the boiler into the top of the soakaway.
If your boiler is below the condense soak away or for any reason you need to pump the condense away, use a Saniflow condense pump.