That is a lot but it's the labour involved in running the pipe-work through the boat that puts the price up. If you can run all the pipe-work through yourself it's a simple job to connect it all up.
If it is a custom made tank then the hardware (tank, valves, pipework etc) will be in the region of £800-1000, but could be more if a pumped system. Might be worth finding out if the boat was offered with a factory fit tank as it might be cheaper to use the same system rather than having a one off.
That sounds a huge amount of money to me. Have you spoken to Tec Tanks. They were really helpful when I needed a sender for my tank. They were/are the makers of the original tec dek.
have a look at their standard tanks http://tektankslimited.com/waste-tanks-42-c.asp They do everything you'll need to fit it. They will also make a custom tank specific to your requirements.
We had a custom made 300liter tank from a small specialised co in Germany for 1000 euro, and installed it ourselves,
found them at messe, have to search for their name if you like
Tektank was more expensive about 1500 euro iirc, at that time
Does that include the macerator discharge pump and level indicator panel too? FWIW I paid about €7000 to install a holding tank and pump on my last boat a few years ago. I was so shocked by the price I got a 2nd quote from another company but it was about the same. There's a lot of labour involved in the piping especially if you've got more than one heads. I would say that £2600 sounds reasonable but as ever, its worth shopping around
I just had a 80ltr stainless blackwater tank custom made at around £800, I think a tektank would have been about the same. As others has said the piping, valves, pumps, thru hull and thru deck is a bit more and not unlikely another £800 (long lengths of good non smelly piping is expensive) in material only and getting it all in place could be a 10 hour job depending on the boat which get you to the £2600.
Modern boats usually have the blackwater tank installation as part of the design and if smartly done it may very well be a 5 hour job so if it was me I would figure out how the install would be made and then asses the cost etc.
If you are running charter on the Thames, surely she must already have a holding tank.
So if it is a question of a larger capacity tank, as she is MCA licensed for 9, then I suppose it depends on if that larger tank can fit in the space allocated. If not and it is a question of a complete installation for second tank it seems to me to be reasonable. If on the other hand it is to replace the existing tank with another larger capacity tank, then maybe depending on access it is a little on the dear side.
Although know a little bit about MCA, I know nothing about the Thames licensing and conditions and therefore of course I do not know if they have certain specifications for black water tanks
just a note that most ppl commented on the cost of the actual tank itself or the labour.
A decent diaphragm discharge pump goes from 500+
of course if you fit a plain macerator pump you can get away with 150odd but it's not (in theory at least) the right option.
Having fitted a system myself, it does indeed involve a LOT of head scratching and testing to get it to fit and route all the pipework...