30 I can see no warrant for reading down the scope of s 157 or s 16 by reference to s 15. As the Deputy President himself said, s 15 creates a separate cause of action for polluting water. True, it may overlap with s 157 or s 16 in some situations. But essentially it is directed to different subject matter. Among other things, it is directed to damage to water rather than damage by water. Subject to one matter, to allow a claim to be made under either (or both) of s 15, on the one hand, or s 157 or s 16 on the other, in respect of damage suffered by a person due to the polluting of water by toxic water that has flowed from the works of an Authority or from the land of another person (as the case may be), does not seem to me to be inconsistent with or repugnant to the terms or policy of any of those provisions. The qualification is that s 15(2) would, if appropriate by-laws were in place,[26] provide a defence to a saline discharge claim under s 15(1)(c), being a defence that could be avoided by making the claim under s 157 or s 16. However, that matter does not justify reading down s 157 or s 16. Parliament expressly limited the potential s 15(2) defence to claims under s 15(1)(c). Had it so desired, Parliament could easily have created a similar defence to claims under s 16 or s 157 based on saline discharges. But it did not. A moment's reflection throws up likely explanations. A claimant under s 157 or s 16 faces hurdles not faced by a claimant under s 15. Under s 157 the claimant must establish a flow of water from the works of an Authority onto land. It must then be found that the flow was the result of intentional or negligent conduct on the part of the Authority;[27] and that such conduct occurred in the exercise of one or more of the functions of the Authority specified in s 157(1). A special form of proportionate liability applies[28]; and there are other special limits on the assessment of damages.[29] Correspondingly, under s 16, the claimant must establish a flow of water from the land of a person onto other land and must establish that the flow was not reasonable, taking into account the lengthy list of considerations set out in s 20. By contrast, subject to s 15(2), a person who pollutes water, whether or not authorised to do so, and thereby causes another person to suffer injury, damage or loss, is ipso facto liable to pay damages to that other person. Understandably, Parliament has chosen to make provision for protection against that particular "strict" liability in specified circumstances. There is no reason to believe that Parliament intended that protection to extend to cases where, for example, the flow was not reasonable or the conduct of the Authority was intentional or negligent.