Trying to get together the layout of the water system for a new house and read that the shower water should go through the grease trap and not the septic tanks.

2 upstairs bathroom toilets hit one septic tank and a downstairs bathroom toilet hits another tank. Also have a medium sized grease trap to capture the sink water. Not sure where the shower water should go as getting conflicting reports

If you have two-chamber septics shower goes into the second chamber, otherwise straight to the leech field, you do have a leech field don't you

Grease trap only needs to be on kitchen sink unless you are a particularly slimy character

My biggest regret about the construction of this house is running my gray water into one or other of the many septic tanks around the house rather than into an underground tank for the garden water.