Her in my neck of the woods, The SWRQCB will not let you dump into a dry well. In my neck of the woods, you need to have a filter that is approved by the sewer agencies. You must also, every year or so, get testing of the samples of the Grey Water before, during and after processing. This test is about $1,000 to $2,500 per test. We have to pay.
For example, we just did a City Parking Garage here in California. In the conference before we did the work, there was 17 people representing the different departments associated with the garage and the cleaning. I had 17 bus. cards with cell phones for problems that may arise. Each person is for a different situation.
The EPA reps was in a truck filming our cleaning with ticket books in hand. They parked outside in shifts of 8 hours. We worked 16 hour straight . We had two inspectors there during that time for 3 days. They walked the job site at their leisure ( Usually every 40 minutes). They took sampling of the water from the filter. And they parked 25 ft from the storm drain with their camera on their dash focused on the drain. During the job we had 5 people from 5 different agencies doing a surprise inspection at different times of the day, one inspection was done at 3 am.
The City of Concord has just passed a law requiring all pressure washer's who clean cement with just hot water (without detergent ) to filter (lightly their water before it goes down the storm drain.
In all cases, dry wells are to be used by the facility of where they were installed only and is not intended for pressure washing. We will be asked to cease the cleaning. If continued, we will get fined.
The theory behind that as explained to me is this. Lets say the dry well is not maintained or is not able to handle the waste for what ever reason. Who is responsible? The owner, who will most likely denied that he gave you permission to dump into his well, or the pressure washer who said he had permission to dump. By having your own filter on site, the EPA has a clear channel to go after you if your filter is not maintained or is having issues.
So if your state lets you dump into a dry well, be advise, that is going to change. Our State catches you, it is a $10,000 fine for the first offense. All ready, one county has fined over $132,000 for pressure washers using a dry well and or no filter. Shoot, if I could do what you guys do, I would be done in 1/2 the time.