[LazyPup]

To answer the question about allowing the sink to just drain outside? No, definitely Not. Discharging any sewage (blackwater or graywater) is a major violation of the plumbing code, Federal EPA regulations and state and local health codes. In the case of EPA regulation, the fines can be as much as $10,000/day for every day of proven offence. State and local authorities would most likely issue a cease and desist order and require the entire structure be inspected and brougth up to code. They can also rescind your "certificate of occupancy" and order you to move out of the structure, (which is commonly done) Ask any General Contractor or Foundation contractor and they can tell you, before they even begin setting forms for the foundation, they consult the plumber to compute what the minimum floor elevation will have to be. In situations where you can not meet the required pitch to the septic tank or sewer, provisions have to be made to install a holding tank lift stations which is a very costly project an one which is done far too often because the builder set the foundation without computing the run to the sewer.