Many water softeners do not need a power supply (twin tank models), so this is a red herring! You need to isolate the softener by doing what I suggested earlier. Of course this is assuming the brine from the regeneration process is passing through your problem waste pipe. We need to confirm that...
Have you eliminated the water softener? Turn off the hard inlet and soft outlet and open the by-pass valve. It could be that the softener is stuck in regeneration mode
Belt and braces approach is called for! It seems you are more concerned about your hard water (you should be). A water filter will not solve this. You should invest (and I say this as good advice) in a modern twin cylinder water softener and get a water filter installed at the same time.
Do it...
Ideally you should fit an isolating service valve to both hot and cold feed whilst you are doing this work.
You don't necessarily have to use the flexi that Brita have supplied. Many plumbers are a little sceptical about flexis. Here is your opportunity to do a good plumbing job, just like the...
Brita instructions are very clear. They are also very supportive as they want their system to work! I have a Brita Torlan and found a drip coming from the spout (after three years). I called them and they sent a replacement cartridge FOC.
What model do you have - it helps if we know!
Do some research, plenty out in internetland
Drinking (hard water) and garden supply must be tapped off before softener.
Preferred models use block salt, easier to handle that granular/pebble salt.
Stuff (magnetic/other) that attaches to cold water supply is like snake oil
In fact do a...
I agree with Shaun, however we should ask the question "Was there any condensation on the rising mains before you installed the softener?
With the softener by passed the water into and out of it will equate to the same temperature as it's surroundings = should be no condensation. However you may...
Fairly common in Spanish properties, normal to have one in the bathroom. We had one in our Spanish house but never suffered from any smells from it. The smells normally came via the shallow 'u' bend in the shower which needed 'topping up' if we were not there for a period of time
Harvey/Kinetico. Both have two cylinders, both use block salt. Pricey, but think of a water softener as a long term investment.
You buy cheap, you buy twice!