Just thought I'd post an update in case it's of help to anyone who finds themselves in this situation. I wrote to Yorkshire Water requesting a copy of the original bill. I told them my name had been added to the account without my permission, but that I wanted to settle the matter with them directly. They wrote back saying they have cancelled the charge in my name in full and requested that the DCA remove the default they had registered for non payment of the bill. Westcot have since written to me informing that they've closed the case, so I'm very relieved. Really impressed with how Yorkshire Water dealt with the matter and also thankyou to everyone who replied on here.

It's entirely likely she may try to argue she paid towards it. I would try to claim back the lump sum of the NPower bill, I do still have the authorisation codes for that payment and I believe another 'friend' has been supporting her financially for the past year, so she's unlikely she's been lifting money regularly from her account which she could claim she's been giving me. She's certainly never bank transferred me any money. She did speak with NPower last year and make a couple of small payments totaling maybe £15 (I'll have to look it up) then stopped the payment plan, I would imagine without speaking to them. I know she's ignored loads of warning letters from NPower and YW as she lived with one of my friends for a few months last year (before being kicked out for not paying bills) and he kept telling her she needs to speak to them or me about it, not just ignore it. He's had bailiffs turn up at his house looking for her after she moved out, so she's burnt another bridge with him. I'm not sure how in depth the courts look into character, but she has a lot going against her, whereas I've made contact with the companies involved (and her) to try to settle the debt. I know at the end of the day, it'll come down to my word against her's and there's always the possibility she could just lie in court. Also the process of actually recovering any money is likely to be difficult and not worth it, if she still refuses to co-operate. I'll send the letter detailing a proposed payment plan at least and see if it pricks her conscience.

Thanks again, it's good to know it's not likely to show as a default. I would pay YW directly as I know DCAs can add on all kinds of admin fees. I can afford to pay it in one go, so I'll probably do that so I know it's done with. I'm considering getting a bit of legal advice, but am wondering if I can try to get her to sign a contract which admits she owes the money. Something along the lines of a letter before court action offering her the chance to pay back a small amount of a few pounds a month to me and knocking a small amount of what she owes as a goodwill gesture. If she refuses or doesn't respond, I'll issue the court papers. Then if she stops paying I'm guessing my case may seem stronger to the court.

Thanks for replying kjun. I will pay the outstanding money tommorrow I think, at least then I don't have to worry about a potential CCJ. I had thought about taking ex housemate to small claims, but we had no formal contract of who was paying for what, just the joint tenancy agreement. I'm not convinced my claim would be successful. On the other hand, she had made a couple of payments towards the water bill and there was a payment plan in place with NPower, so it might be worth looking into a bit further. I do have several Facebook messages from her in which she admits she owes the money, but I would have thought most Judges would dismiss that as evidence as it's not a formal contract? Also, it's fairly likely she may just not turn up to court on the day, she has a bury her head in the sand approach. She wouldn't have the money to repay me if I won, but I guess any token amount of money I get back would be a bonus. If it's a reasonably cheap process it might be worth it to show her that her behaviour is totally unacceptable. I could send her a notice before action as I have her current address and see whether that shocks her into facing up to her responsibilities (doubtful). Does anyone have any opinions on whether this is worth doing? Tips to make sure I have a strong case, or any information on similar cases that have been successful/unsuccessful.

Thanks Brigadier. To my knowledge there's no default showing on Equifax (need to check Experian next) and she must have stopped paying for the water well over a year ago judging by the amount that's outstanding, so hopefully I've avoided a default. I read that Yorkshire Water have started recording defaults on missed payments, so that made me panic. I'm just trying to limit damage to my credit at this point, the loss of money is frustrating, but not being able to get a mortgage for 6+ years is more of a concern at the moment. Am I right in thinking if the debts get paid off any outstanding debt traces will fall off faster than 6 years? I will pursue the fraudulent change of account avenue with YW and see what response I get. I wasn't sure whether they would argue that by me being on the tenancy agreement and using the water I was somehow agreeing to a contract with them. I certainly didn't sign any paperwork or give them my personal details. I figure I have nothing to lose by writing to them. Would they have to provide evidence of either a signature or phonecall in which I allegedly gave my permission to be on the account?

In 2011-12 I was in a house share with a girl who turned out to be incredibly bad at paying bills and I've since found out has bailiffs chasing her for a substantial amount of debt. I had the electric and gas bill with NPower in my name and she was supposed to have the water bill with Yorkshire Water in her's. My DD to NPower was always paid on time, but we had a lump sum to pay at the end of the tenancy as we'd been under paying. I paid my half off and she set up a payment plan for her remainder of the bill. A few months passed and I received a letter from a DCA, not surprisingly the ex-housemate had made a one off payment for £5 then did a runner, leaving me to settle the rest. I checked my Equifax report and couldn't see a default, but there were a few tracking searches from a couple of DCAs . I've just received a letter from Westcott demanding payment of £150 for the water bill. I challenged this, as I didn't consent to my name being on the bill, but it seems she must have given my details and had me added and then intercepted the unpaid water bills so I didn't see she hadn't been paying. They stated my name was on the bill and they don't get involved in third party disputes. It does seem odd that Yorkshire Water would do this as I've been told in the past by utilities companies that they can't add another party to a bill without speaking to them or having a signed letter. We were on a joint tenancy, so I'm guessing I have no recourse to have my name removed from the bill and have Westcott chase her for the debt? I will pay the bill off in full if this is the case, but I'm concerned about the affect this might have on my credit score. I was planning on applying for a first mortgage next year but fear I may get defaults from Yorkshire Water and NPower because these accounts were in collections through ex housemate not paying/hiding correspondence. Is it correct that defaults can only be placed 6 months after the first missed payment? Is there anything I can do to appeal if they decide to issue a default given the circumstances. Otherwise my credit record is pretty good, I've always paid bills on time and don't have any other outstanding debts. I realise all mortgage lenders look at different criteria, but is it generally really damaging to have tracking searches showing?