It has been observed that people are frequently throwing garbage in drains of Mumbai after the deep cleaning drive, a BMC release on Wednesday said, adding that dumping waste in a drain blocks the wastewater drainage. "People should not throw garbage again in the area where the cleanliness drive has been carried out, otherwise the cleaning efforts become futile. People should not throw waste in drains at any place," it said. The civic administration is considering taking strict punitive action against violators, the BMC said. Around 3,700 workers were employed for the deep cleaning drive, besides 33 earth-moving machines, 148 dumpers, 21 compactors, 69 water tankers, nine road sweeping machines, seven misting machines, six suction machines, and three litter picker machines. Roads, footpaths, gutters and drains are being cleaned under this campaign.