With reference to Richard Whatmoor's letter (NCE 20 July), the long-term effects of leakage repairs on building foundations can only be assessed on a site-specic basis.
It is conceivable that such an old property (built 1865) may have had exceptionally shallow foundations and shrinkage damage may have resulted without substantial trees nearby. In this scenario a repaired leak in 2006 may be a good thing, possibly avoiding long-term softening of the soil beneath the 1992 underpinning.
Alternatively, a repaired leak could adversely affect unusually shallow foundations on clay soils if leaking moisture had provided protection against prolonged droughts over the years, thereby postponing the need for underpinning.
In another case, substantial trees could develop a deeper root structure in order to maintain the moisture uptake if this source had been cut off at a shallow level following a repair.
In this case, non-underpinned foundations of moderate depth may even be at risk. There are many combinations of factors with varying degrees of risk, according to the specic circumstances.
Of course, water companies themselves will not be responsible for repairing leaks on private land so the potential effects may be sufciently remote from a property anyway.
Alan Watson, alan.w@soilconsultants. co. uk