A $15,500 waste audit has given the city of Hamilton a glimpse into the recycling and green bin habits of single-family homes.

The 100-home audit showed that there has been an increase from 50 per cent to 55.1 per cent in waste diversion since a previous audit was done in 2009. This means of all the waste discarded, 55.1 per cent was placed either in the blue box or green bin rather than in the garbage.

There was also a slight increase in participation level for green bins by 2 per cent, or two homes. But there was a dip in capture rates: the percentage of organic waste discarded that actually lands in the green bin, rather than the trash or recycling. Food waste capture rates decreased from 56.5 per cent in 2009 to 44 per cent in 2012.

"That’s quite a significant drop," Adam Watson, a Policy and Program Analyst for the City, said, adding it’s not clear what contributed to the drop.

"We’re not concerned, but we are confused."

The survey took place during a two-week period in June and the results were presented to the Public Works Committee earlier this month. The 100 single-family homes surveyed were scattered across 10 different neighbourhoods in the city.

The results also showed the waste included about 7 per cent uneaten food that had gone to waste — whole, uneaten bananas, for example — amounting to 9.8 kg of wasted food per household per year. As well, blue box participation rates had dropped 19 per cent.

On the bright side, the amount of waste generated per household decreased by approximately 3.96kg per week — a 29 per cent decrease.

According the Watson, the detailed survey allows the city to look at a specific slice of the Hamilton population — single-family homes — but they also track city-wide numbers year round by weighing and comparing the waste coming into facilities.

"But all the materials are mixed together when it comes to our facilities," said Watson.

"This [survey] allows us to identify problem materials we could be doing better at capturing."

One example of this would be plastic bags, which were found in all waste streams more often this year, according to the waste audit.

Though the sample size is relatively small for the City of Hamilton — and Watson admitted it would be nice to audit a larger number of homes — for the basic questions the survey aims to answer, 100 homes gives a useful picture, according to Fred Hoppe, a statistics and mathematics professor at McMaster University.

Next year, as the new bag tag system goes into effect, the city will be keeping a close eye on how it affects waste diversion, Watson said. Another single-family home audit is scheduled for 2014.