21.   Braided stainless steel pipe is the most expensive.

22.   But because they were accessible, the pipes were also easy to repair.

23.   But fine pipes cannot be mass-produced.

24.   But other federal officials, environmentalists and an independent expert on pipelines contended that a double-walled pipe would be significantly safer.

25.   But once the federal rule on the pipes was relaxed, there was little incentive to adopt the new technology, he said.

26.   But our pipes are also fragile.

27.   Designed to be just below a tank on the first floor, the pipe was to provide residents with water during the blackout following a nuclear attack.

28.   Does anyone know what this pipe is and what it was supposed to do?

29.   Engineers estimated that the small pipe is able to supply only about a quarter of the amount the normal system supplies.

30.   Exposed pipe is more vulnerable to slowly migrating rocks.