Hello Paul, I think the ...

Hello Paul, I think the reason for the "overkill" falls into two main areas: 1. Risk abatement - Consultants want to ensure they build a solution that works. At the same time they often "over-spec" a solution because they feel the requirement will probably increase over time as population and local industry pressures build up. They argue it is better to build an "over-spec" plant rather than having to build a new one in 5 to 10 years because the inputs have increased. This is a sound argument from a risk management point of view. 2. Vested interest related to the consulting brief - The other significant driver is a more difficult issue. Often wastewater consultants have either a direct or indirect association with engineering firms that build WTP's. These engineers influence consultants, overtly or not, to argue for "over spec" solutions. The engineers then build a solution that generates more revenue and profit for the engineering firm. This is not to say that this quasi-corrupt conduct is happening all the time. It isn't. But it’s potentially a risk in the consulting and capital deployment phase of the WTP project. It is also worth considering that these "over specking" influences by engineers on consultants can be subtle and build up over a long period. For instance, even if the consultant has no direct financial relationship with an engineering group: Ø he or she could have been a water engineer in the past (and maybe worked with the engineers) Ø could have been friends with the engineers for several years (working in an industry where people have lots of common contacts) Ø wants to ensure that the engineers have a successful business. So, the answer to your question is more related to human nature in business rather than a specific technical one.