I was rather depressed to find that your review of the University College London Hospital (23 September) seemed to mention virtually every aspect of the hospital’s construction other than its drainage material.

Increasingly, there are instances where flexible materials are chosen over clay pipes, greatly curtailing the life expectancy of the underpinning drainage with negligible cost saving. More worrying is where hot effluents (for example, under hospital laundries) or aggressive chemicals (under laboratories) are fed into piping systems that are just not up to the job. Too many schemes seem to simply skirt over this issue.