Nearly 100 municipalities in California have banned the distribution of lightweight plastic shopping bags and imposed mandatory fees on the distribution of recycled paper bags. A bill before the legislature, Senate Bill 270, would impose similar restrictions statewide and could cost California’s consumers over $2 billion per year without providing any environmental benefits.

Proponents of SB 270 and other bag bans claim they will reduce litter and protect the marine environment, diminish our consumption of resources and emissions of greenhouse gases, reduce waste and save taxpayers’ money. As we show in a new Reason Foundation study, all of these claims are false.

Plastic bag litter is not an environmental menace. According to the most authoritative study, it constitutes only 0.6 percent of visible litter across the United States. So, even banning all plastic bags would have little impact on overall litter. And, contrary to claims made by ban proponents, it accounts for less than 1 percent of visible litter items in storm drains, so it does not pose a flood threat. Nor does it kill large numbers of marine animals.As David Santillo, a senior biologist with Greenpeace, told The Times of London: “It’s very unlikely that many animals are killed by plastic bags. The evidence shows just the opposite. … On a global basis plastic bags aren’t an issue.”

People concerned about waste should love lightweight plastic bags, which account for about 80 percent of all grocery bags in the U.S. but constitute only 0.4 percent by weight of all waste sent to landfills. Paper bags, which account for most of the remaining 20 percent of grocery bags used, generate the same amount of waste (0.4 percent of the total) because each bag is far heavier. A plastic bag ban might increase the amount of waste produced, as people switch to heavier alternatives, such as paper and thicker plastic bags. And since neither the amount of waste nor the amount of litter produced will fall significantly (if at all), the cost of associated municipal services won’t fall.

Some alternative bags appear to be superior to lightweight plastic on some environmental measures, such as use of energy and emissions of greenhouse gases. But that is true only if those bags are reused a sufficient number of times (ranging from six to 30 or more times, depending on the type of bag). In practice, households do not typically reuse their bags enough to achieve those gains. At actual reuse rates, lightweight plastic bags result in about half the energy consumption and greenhouse gas emissions of alternative bags.

All alternative bags are associated with greater water use. Reusable bags result in the use of at least 10 times as much water as lightweight plastic bags. That assumes those households follow the advice of the California Department of Health and wash their bags regularly. Yet, a recent survey found that only 16 percent of shoppers cleaned their reusable plastic bags at least once per week, even though failure to do so has resulted in serious illness and studies show that about half of unwashed bags contain potentially dangerous germs.

Consumers who spend time cleaning bags have less time to spend on other things, such as working or rearing children. We estimate that if California’s 12.4 million households spent only five minutes per week cleaning their shopping bags, the annual cost would be $1.66 billion. Add to that the money spent on reusable shopping bags and garbage bin liners (more than half of all households reuse plastic bags for garbage) and the total cost rises to about $2.35 billion.

The state bag ban would particularly impact poorer working families, who would be forced to spend more on bags and, if they choose to reuse, on washing their bags. Meanwhile, there is no evidence that the cost of their weekly shopping would fall, even though retailers’ costs might fall slightly.

So, banning lightweight plastic bags would likely increase our use of energy and water and emissions of greenhouse gases, but would not substantially reduce waste or litter or the cost of associated taxpayer funded services. It is difficult to see how California’s political class can justify imposing the more than $2 billion it would likely cost the state’s consumers.

Julian Morris is vice president and Lance Christensen is a policy analyst at Reason Foundation. They are authors of the new report An Evaluation of the Effects of California’s Proposed Plastic Bag Ban.