Not all properties can support a septic system (tank and leach bed). A “Perk” test will need to be completed to insure the soil will absorb the processed effluent. Rocky lands do not accommodate septic systems well.
My Aunt in Connecticut USA had a house on a hillside above a deep fresh water lake. There was no sewer system accessible and the ground did not perk. All the homes around the lake had to blast or chisel holes on the property to install waste tanks that were pumped out regularly when full.
“Gray” water (showers and clothes washers) were allowed to filter separately into ground “leach” lines. Many of the lakes are extinct volcanos full of water.
Assuming you property perks well, check with your controlling government agency to see if a permit is required and size required for your residence size/people capacity. If a sewer system is available, you maybe required to connect to their system (your cost/expense). Placement of a septic tank and leach bed field is critical. Tanks need to be pumped out every six to ten years. Tanker truck will need access with its hoses (and digging equipment, if access cap is not available). If you not properly maintain the septic tank with bio-enzymes monthly (just flush down toilet), the leach bed will clog and your yard become a smelly mess. Michigan law several years ago required my Upper Peninsula (UP) cabin have a septic tank installed since we installed a indoor toilet (were using wooden out-house).
Excavation, planning, and Installation should be done by professional. They have the equipment needed and leach bed materials necessary. A very small shop building can be supported by two 55 gallon drums and leach bed for a primitive septic system. Cutting the line, joining drums, pump out point and venting can be a challenge. Metal drums rot faster than heavy plastic ones. Concrete or brick compartments are best.