I think the best option then would be to relocate the tank as there is very little else in the way of diverting the flow, you can do and keep with the regs.
Thanks. I don't think that is possible. That area, unfortunately, seems the most suitable one for the purpose, but I will ask. I guess the cost would be massive too and have to be justified.
I had an update today, and the have decided to install Keraflo valve, that was mentioned by Nige.
I have then spoken to Keraflo myself and have asked if their valve would be noisier than the normal one and the technician I spoke said that it shouldn't be, so hoping that it is true.
I have then spoken to WRAS asking for advice if I can get exemption from the water regulations and install a silencer pipe, and they said that water regulations are enforced by local supplier, Thames Water in my case, and they can decide themselves if that would be permissible, as they would have to do maintenance, ect.
I haven't spoken to the Thames Water about it yet, but might do so tomorrow after speaking to the project manager. This would be great if allowed, but not sure if the chances of that happening are high. Has anyone got any experience of getting an exemption from the regulations and can advise on the best way of achieving it?
Interestingly, I was warned by WRAS that if the works are undeclared to the local water supplier it might cause all sorts of issues. I would have thought that the local authority would declare these works automatically, but apparently sometimes they do not and that can cause all sorts of problems. Not sure what all this about.