I would like to qualify my answer below - Dingman Township is issuing notices that state "The proposed regulations, as currently written, would not allow permits to be re-issued without additional testing and re-design of the system. etc." Again, this is relative to properties without a house; nothing is mentioned about properties with a structure.

I would most agree with Georgi Schaffer below. However, I just concluded an FHA closing where the bank never asked for a home inspection. One was done anyway, but the bank never asked for a copy. The Pennsylvania Dept. of Environmental Protection (DEP) sets the State's sewage regulations. They are currently being revised and expected to become effective in 2010 and will effect properties that do not have existing homes - septic designs and permits will have to conform to new regs before being re-issued. A caution to those who own property and have not yet built.

The first thing to consider is the township. Most townships require an occupancy permit before you move in.
If you buy the house you may not move in before you fix the problem
The other thing to consider is the mortgage. Banks may have their own requirement. Some may require money in escrow for the purpose. Some may not give a mortgage.
If you are selling a home, you should disclose it.
If you are buying and know there is a problem do you have any idea whether it will be able to perc for a new system? There are a lot of things to consider. Perc tests cost money and take time. Contact a septic company in the area for details..
An agent that you work with will give you more information.

If the buyer is paying cash it can be sold. Lending institutions will require it to be working.
Contact the sewage inforcement office in the township that the home is located.

Sold "As Is" generally means that the house is sold with all existing defects whether they are know or not. Anyone looking at a house being sold "as is" should realize that there are going to be problems/defects/repairs; obviously the house is in less than perfect condition.
The mortgage lender may require the house to be in a certain condition.
If you rent it out, you are required by law to provide certain basic necessities that make the dwelling livable; I believe one of those is a functioning toilet.
But to sell a house without functioning anything is acceptable as long as all known defects are disclosed.