Ever heard of “demon snowballs”? Likely not, and it is probably putting images in your head of something cold and wet. Well, these demon snowballs are generally wet – but are not formed by snow and are not wonderfully white. These “snowballs” are wet wipes, and are called demon snowballs by wastewater treatment plant operators because of the way they get stuck in wastewater infrastructure. How is this relevant to ocean lovers? Wet wipes are a common type of marine debris – entering the environment via untreated and treated wastewater.
Although you may throw your wet wipes in the trash can – which is the best thing to do with them – many wet wipes are marketed as “flushable.” Flushable, or non-flushable, wet wipes are manufactured as non-woven sheets of natural and manmade fibres – including cellulosic materials like rayon and/or plastics (Munoz et al. 2018). Wet wipes usually have a high wet-strength, because synthetic fibers retain their form, shape, and strength in a moist state. Maintaining their form, and being strong, are desired properties for wipe manufactures so the product will not fall apart while you use it.
When flushed, wet wipes enter the sewer systems, where they are assumed to move along with wastewater to treatment plants. However, their transport depends on various factors such as pipe diameter and slope, flow rate and velocity, plus the amount of product discharge.
If a significant amount of flushable wipes are discharged into a sewer system over a short period of time (a few hours), they will accumulate in drains, forming large “white” balls (a.k.a., demon snowballs), and lead to potential sewer backups. Holiday weekends, such as those in summer where people congregate, are an example of times when the amount and frequency of discharge at a single location may increase due to families and friends visiting each other. Likely not something you think about when you convene for a family weekend at the beach!
When we flush our products down the toilet, it absorbs and blends with other waste we send via our households such as food waste, fat, oil and grease (called FOG by plant operators), shampoo, human hair, and cosmetics. When flow is intermittent and low as our household plumbing, flushable wipes settle in our sewer pipes, accumulate over time, and can cause back-ups followed by sewer overflows. At treatment facilities, wipes clog and damage wastewater equipment such as screens, pumps, grinders, mixers, and sensors that require complete replacement or extensive repairs – hence demon snowballs.
As examples, in England and Wales, approximately 4,000 cases of pipe blockages and property flooding are reported each year (Jeyapalan 2017). In the USA, 400,000 basement backups and 50,000 sewer overflows are documented per year (USEPA 2001). The City of Toronto, Ontario has approximately 10,000 calls a year for reported blockages. Unfortunately, wastewater utilities from around the world have been reporting that wipes are responsible for most pipe blockages and pump clogs in sewer networks. These reports have been published as a series of articles in various languages, and in well-known newspapers such as New York Times (Caron, 2018), The Guardian (UK), and the National Post (Canada).
Consumers assume that “flushable” products must have been tested rigorously for their compatibility with household plumbing and sewer systems. In contrast, there is actually no standard definition of what is flushable, and no standard method to assess flushability. Wastewater engineers are trying to work with governments to help define technical characteristics of flushable products, so that we can clearly differentiate the products that are truly “flushable” from those that are not.
For now, to keep our plumbing “snowball free”, we must not treat wet wipes – whether they say “flushable” or not – like toilet paper. Their size, strength and material composition prevent them from breaking down in wastewater systems, and even if they break down, they may contribute to microplastic pollution in the environment. The bottom line – stop flushing wipes.
Blog written by Barry Orr, spokesperson for Municipal Enforcement Sewer Use Group (MESUG), of Ontario and Faith Karadagli, Associate Professor of Envrionmental Engingeering at Sakarya University, Turkey.