Flushing Money Down the Drain

It’s time to recycle more of Maui’s wastewater

Water is a precious commodity in Hawaiʻi, despite our islands being home to some of the wettest places on Earth where rainfall is recorded in the hundreds of inches. Proper management of this resource is complicated, but it doesn’t make sense to pump usable water into the ground when dry conditions persist throughout many of our microclimate zones. 

ccPixs.com / courtesy flickr

Maui is experiencing drought conditions, with historically low rainfall and stream levels being recorded all over the island. As we find ourselves in the dry season, parts of the island are likely to face shortages of potable water—the water we typically use for domestic purposes and agriculture. The areas that will be most affected and hardest hit—including Upcountry, Central Valley, and West Maui—rely largely on surface water for their potable needs. Ironically, all across Maui, potable water is literally going down the drain every time we flush our toilets. At the same time, Maui County is injecting millions of gallons of recycled water into the ground—water which taxpayers are paying the county to treat—that could readily be used for agricultural and irrigation purposes.

Before you judge what is going on and who to blame, let’s consider how we got here. 

Our relationship with water and waste is continuously evolving and remains far from perfect. Being able to flush, rinse, wash or drain our waste has been a boon for hygiene and our quality of life. Yet most of us never consider what happens to those things that go down the drain—neither the waste nor the water.

If you’ve had the pleasure of using a simple pit toilet/latrine/privy, we can agree that the flush toilet is much more pleasant to use. The pit toilet with a flush added—aka a cesspool—is still very much in use these days; the Hawaiʻi Department of Health estimates that 12,000 such toilets are active on Maui alone. This means that whatever you flush into the perforated tank either sits and drains into the surrounding soil or seeps into cracks in less-porous rock or has to get pumped out periodically. In theory, the pathogens contained in the waste die and other substances such as nitrates break down over time.  Unfortunately, in very permeable soils, or in cases where cesspools are close to bodies of water or the ground water table, it is common for pathogens and nutrients like nitrates to contaminate these water resources. The state of Hawaiʻi finally decided that cesspools were not a good idea in 2017 and will now require all cesspools to be replaced by 2050, but that is a long time off.

Septic systems are upgraded versions of cesspools in that they include a treatment system, typically a leach field. Since 1991, the Hawaiʻi Department of Health has required the installation of septic systems rather than cesspools in new construction. With these more advanced systems, when they’re functioning correctly, the waste liquids run out into a network of pipes, and contaminants get broken down by naturally occurring soil bacteria. Because the liquids drain over a much wider area than a cesspool, the process is far more efficient. Solids are retained in a tank and composted to some extent, but still need to be periodically pumped out. However, when septic systems fail to operate as designed, they pose similar pollution problems to those created by cesspools.

While cesspools and septic systems can—and have been—scaled up to serve commercial buildings, apartments, and communities, they are most typically built for use at private residences. As we examine systems built to handle sewage collection and treatment for entire communities and large developments such as hotels, we find that these projects are designed at an industrial scale to be both cost-effective and efficient. Defining “treatment” can be difficult as the process varies from place to place and even by type of activity. Before 1972, it was perfectly legal to run a long pipe over the reef and dump the wastewater from a sewer system right into the ocean. And that was exactly what was happening on Maui until roughly that year. 

Things changed when the 1948 Federal Water Pollution Control Act (which you probably know as “the Clean Water Act” or CWA) was amended in 1972, 1977, and 1987 to protect “the nation’s waters.” And these amendments radically changed what could be discharged legally into any body of water—rivers, oceans, or wetlands—without appropriate authorization. Notably, the CWA does not include groundwater but rather surface waters only. Due to this unfortunate omission, private entities and local government on Maui started to transition from sewage outfalls impacting surface waters to injection wells that can contaminate groundwater.

Injection wells are essentially wells in reverse—rather than pumping something out of the ground, they pump something in. When injection wells are used to dispose of wastewater, solids are removed, and the water may be treated to some degree—for example, to remove pathogens—before being pumped into the ground. The removal of solids is practical—they would otherwise clog the system. Much like cesspools and septics, the theory with injection wells is that any other contaminants will be degraded over time, but we know now that this isn’t always the case. 

The general approach to wastewater disposal, even today, has been to separate the solids from the liquids and hope the contaminants in the liquids naturally degrade in the ground. Unfortunately, while these systems allow our waste treatment to be out of sight and out of mind, for the most part, it is clear that these solutions do not work as well as advertised. Injected wastewater from the Lahaina Wastewater Reclamation Facility has now famously been shown to bubble back up along the Lahaina shoreline in as little as three months and to have had damaging effects on the reef along Kahekili Beach Park. Modeling of the plume from the injection well at the Kihei Wastewater Reclamation Facility suggests that injected water from that system is returning to the surface along the coastline by Kalama Park. It is worth noting that county injection wells are not the only ones with problems. The private injection wells at Maʻalaea have similar issues and the Maui County Council recently approved a proposal by Council Member Kelly King to develop a new wastewater treatment plant for the community to allow the closure of those wells.

Courtesy Maui Island Water Use and Development Plan

Considering that it’s been 50 years since dumping raw sewage into the ocean around Maui (and the nation) was banned, we still have a long way to go when it comes to effectively and safely managing our wastewater. For instance, Maui County would love to use its treated wastewater, also known as R1 water, for other purposes. However, R1 water is not suitable for drinking,  so it needs its own distribution system. These systems are being built and Maui County is slowly expanding them. If you’ve been in Kihei or Lahaina and seen purple pipes or utility covers, these are indicators of recycled water being used. R1 water is perfectly safe for use in agriculture and landscape irrigation. Indeed, the nutrients in R1 water that are so bad for coral reefs are actually beneficial for irrigation use in that they provide free fertilizer. 

While making greater use of recycled water saves our potable water for more important uses, like drinking and hygiene, it will require the political will to put the necessary money into building the infrastructure to support it. Until R1 water is piped to where it can be used, it is simply not an option for those that might want it. Those with uses for reclaimed water or who feel that using recycled water on Maui or statewide should be a priority, must let their state representatives and county council members know. 

Hawai’i’s water resources are limited, and under greater stress during the current drought. Also, less water down the drain means less wastewater! Try some of these easy water conservation tips.

TIP #1 – Don’t let your faucet run

Turn off the tap while brushing your teeth or shaving. In the kitchen, rinse food off of dishes and utensils, then fill the sink with soapy water to clean them, drain and then give your dishes a final rinse with clean, hot water. 

TIP #2 – Check your house for leaks

A little leak can waste a lot of water. A slow drip on a faucet can waste 25 gallons in a day. To check for less obvious leaks, turn off water through the whole house and any outside irrigation. Check your water meter. Check it again about two hours later. If it has moved, something’s leaking. Check toilet leaks by putting a few drops of food coloring in the tank and waiting 15 minutes. Any color in the bowl indicates a leak.

TIP #3 – Take shorter showers

Depending on your shower head, each minute you shower uses three to six gallons of water. Get wet, soap up with the water off, then rinse. How many gallons can you save?

TIP #4 – Use water-efficient fixtures

Modern plumbing fixtures are typically much more water-efficient and provide the same function as older, obsolete fixtures. An aerator on your kitchen faucet can save five gallons or more each day. A modern low-flow toilet can save five gallons or more every flush. A modern, efficient showerhead can save you up to five gallons every minute without sacrificing pressure. 

TIP #5 – Water your lawn less than twice a week

Lawns should not be watered every day. Watering once every three days promotes deeper root growth, making your lawn healthier and resilient. Bonus: Nutgrass—a weed that thrives in wet environments—will often die off if you water less. 

TIP #6 – Water your lawn in the dark

If you run sprinklers during the day, you’re not watering the lawn, you’re watering the air, as the sun will evaporate a lot of that misty spray before it makes it to the ground. It is best to water between late evening and early morning. Doing so will ensure your water soaks deep into the ground and encourages your grass to grow deep and resilient roots.

TIP #7 – Use a nozzle on your hose

A running garden hose can pump out hundreds of gallons of water in just a few minutes. Using a nozzle makes sure you only use the water you need when watering your plants, rinsing your gear, or washing your car.

John Starmer