DS4000 SEPTIC TANK 4000L PREMIUM consistent with the EN 12566-1 normDS4000 SEPTIC TANK 4000L PREMIUM consistent with the EN 12566-1 normDS4000 SEPTIC TANK 4000L PREMIUM consistent with the EN 12566-1 normDS4000 SEPTIC TANK 4000L PREMIUM consistent with the EN 12566-1 norm