Query regarding overflow of septic tank

Dear Sir,

We live in Nanmangalam, a 14-house apartment complex in Chennai. The 15-foot septic tank overflows almost every week due to incorrect construction since it includes all the kitchen water. What is the most cost-effective way to fix this issue? Please note that there is no garden or drainage system in our area if water is purified. Previously, the water was left in an empty field near us, but now the construction has begun on that plot so we are looking for a cost-effective solution.