QUICK ANSWER

Apartment and condominium complexes in Colombo and suburban Sri Lanka generate significantly higher daily wastewater volume per plot than a single house, and typically rely on a shared system serving many households at once. Parawewa systems for multi-unit sites are sized to combined occupancy (roughly 180 liters/day per resident in our capacity model) with Option B recommended where basement or underground parking limits gravity discharge depth.

Apartment developers face a different engineering brief from a single homeowner: one shared wastewater system has to reliably serve dozens of households, with zero tolerance for the kind of service disruption that would affect one house at a time in a suburban setting.

What Changes at Multi-Unit Scale

  • Higher Combined Daily Volume: Our sizing model allows roughly 180 liters/day per apartment resident — meaningfully higher than a single-family home estimate once dozens of units are combined.
  • Basement and Underground Parking Constraints: Many Colombo apartment developments include basement parking, which can restrict the depth available for gravity-fed discharge, making Option B, the Seal Type Parawewa System, a common fit.
  • No-Disruption Requirement: A shared system failure affects every resident simultaneously, making the 10-Year written warranty and gully-bowser-free maintenance profile particularly valuable at this scale.
  • CEA Compliance at Scale: Larger multi-unit developments are more likely to require formal environmental clearance — see our CEA compliance guide for the discharge parameters involved.
Real Installation Reference

An apartment complex in Kohuwala is a real example of this multi-unit category — a shared system serving many households on a single, space-constrained plot, the kind of site this guide is written for.

Because every apartment development has a different unit count, basement layout, and occupancy profile, our engineering team recommends a site consultation early in the design phase — ideally before foundation work begins — rather than retrofitting wastewater planning after construction is underway.