W salam.
Most of the architects recommend septic tanks in porch in their drawings and that is the best location of septic tank. Lawn should be clear of all concrete structures. Another reason for placing septic tank in porch is that in houses which are 5 marla 8 marla or 10 marla, open passage is at one side whose access is from porch. In that case sewer lines coming from rear and side passages is joined straight into the septic tank. If septic tank is in lawn then there will be requirement of separate manholes or 45 degree elbow to connect the sewerage line to septic tank which is not recommended.
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