I have skimmed through all the "advice" and found the most correct is ( unusually ) Goldberg's.
The reality is that the landowner installed the pipe over HIS land to ( then ) HIS cottages. He did not bury them at the Water regulation depth of 750 mm ( because the Water Regs had not been written then ) BUT 3' was still the "normal' depth then.
The water regs have been around longer than you Tony
The cottages were later sold and the conveyancing solicitor failed to determine the water supply derivation or obtain a wayleave for it.
How do you know that until the OP checks the Deeds, I would expect it all to be there in black and white
The tenant farmer did not know about the pipe and when ploughing at normal ploughing depth (???) dug it up as it was only at a lesser depth. At the BBC we usually had to put cables and pipes at 1.2m depth as "deep ploughing" could be down to 750mm. Regardless the farmer has done nothing wrong!
The Farmer has busted the water main, and lashed up a surface repair, that will freeze given the first frost
The freehold landowner installed the pipes and should have warned the tenant farmer when granting the tenancy. He failed to do that!
That's a BIG assumption
My conclusion is that the Freeholder and the first conveyancing solicitor were at fault.
How do you work that out when you don't know
Since all this happened over six years ago the Statute of Limitation is likely to be used as an excuse for nobody to accept any liability.
If I was your solicitor, or better still your Surveyor, I would aim to negotiate a settlement on the basis of the landowner granting a formal wayleave and the farmer/you burying the pipe at an adequate depth so that no further damage would occur in the future.
If you was my Solicitor or Surveyor, I would expect you have get the correct information, and then telling the farmer to get his arse in gear or you have his guts for garters
I appreciate that you may feel that you have done nothing wrong. That may be so, but to protect your own interest you should have wondered how the water got to your taps. An astute buyer would have ensured his solicitor sorted out the water supply before the purchase was completed.
Thats is Boll---ks and you know it.
If I had failed to sort out the services properly when buying land for the BBC then I would have been sacked from my job as a senior site acquisition engineer! No water, no toilets. No electricity, no transmitter!
Tony