Eco-Experts Answers Your Environmental Questions

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Caroline Blazovsky
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Carol Steinfeld
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Pete Nichols

Detergents in graywater

Is graywater containing Wisk detergent safe for lawns and plants? The detergent, called Wisk Action with Colorhold, is labeled “biodegradable with no phosphorus and safe for septic systems.”
–Kitty Jansen Arena, Wisconsin

Carol Steinfeld replies:

Most soaps and detergents won’t kill plants outright. Some even feed them. However, some ingredients can clog plants’ “arteries.” Soaps emulsify soils, microbes, and liquids, detach them from surfaces, and act as a surface action agent (surfactant) to reduce water’s surface tension, making it “wetter.” Detergents go a step further, detaching and binding up particles so they can be washed away.

Many soaps contain sodium hydroxide. This increases the amount of sodium in the graywater, while the hydroxide raises the pH, or alkalinity. Sodium can inhibit water and nutrient transport in some plant cells and change the osmotic balance. In other words, sodium causes hypertension in plants, just as it can in humans.

Wisk only lists its ingredients in general terms, but it appears that it will not harm gardens irrigated with graywater. If you are planting salt-sensitive plants, look for potassium-based laundry soaps instead. Potassium is a fertilizer and a beneficial nutrient. Most liquid soaps are made with potassium hydroxide. Potassium hydroxide serves as an excellent grease remover; it works by turning grease into soap. Tri-potassium phosphate (TKP) is a powerful cleaner that is used on sewer pipes and automotive engines.

Citrus oil soaps are also a good choice for graywater gardens. Laundry powders (both detergents and soaps) often contain caking agents such as silicates to keep them powdery, even in products labeled “natural” or “organic.” These and other additives called “builders” do not decompose and can clog graywater-irrigated gardens.

Phosphate laundry detergents are banned by most states because phosphorus can pollute surface water with nutrients. But your plants will eat it up.

Carol Steinfeld is co-author of The Composting Toilet System Book (Chelsea Green, 2000) and conducts workshops on composting and composting toilets.

Home heat conversion

Many homes in rural North Carolina and Virginia are heated with propane gas. I object to the odor and the expense of the fuel. Is it economically and/or physically feasible to change a 1,500- to 1,700-square-foot home’s heating system from propane gas to natural gas, or even to an electric heat pump? I hope to do this in conjunction with (at least passive) solar heat capabilities.
–Elissa Ornato via e-mail

Pete Nichols replies:

Unfortunately, this question doesn’t have a direct and simple answer. The reality is this type of heating system might make sense for you but not your neighbor. I understand your concern about the propane scent and your objection to its cost. Propane gas is actually odorless in its natural state, but when it’s used to heat homes an odorous additive is required to detect leaks.

The main factors in heating efficiency are the cost of the energy source, the type of appliance you use, how well heat is distributed throughout the house (and how well it stays there), and the cost to maintain your existing system.

Based on recent average energy prices in your area, natural gas is about 60 percent more economically efficient than propane. Most heating systems can easily and inexpensively be converted from propane to natural gas with readily available conversion that lets you replace the orifice at the gas outlet port. Contact a local HVAC professional to ensure your existing gas lines are sufficient for the conversion.

While you’re at it, check out how well your system is distributing heat and how well your home conserves it. If your ducts leak to the outside or pass through uninsulated areas (such as crawl spaces), much of the heat is being wasted. Also check whether the heat is quickly dispersing. Air leaks throughout the house (around windows, doors, plumbing chases, foundation to wall junction, etc.) are notorious energy wasters. A thorough air-sealing mission (to “tighten” your house) is usually the most cost effective way to save heating dollars. You can perform this yourself with caulk, weather stripping, and low-expansive foam, or hire a professional to do the job.

Converting to an electric heat pump is extremely efficient, but costly. If you don’t need to replace your heating ­system, I would wait on that and ­concentrate on tightening your space.

Pete Nichols has an extensive background in green building materials and technologies and is the founder and marketing manager of Sustainable Flooring, a bamboo and cork manufacturing cooperative ( He is also a co-author of the upcoming book Green Remodeling: Changing the World One Room at a Time.

Safe flea control

Do you know of any natural ways to get rid of fleas in the home without toxic flea bombs? How can you keep them off your pets?
–Dave Burger Pennellville, New York

Caroline Blazovsky replies:

Finding alternatives to chemically laden insecticides is one of our biggest challenges in creating a healthy home. Instead of a flea bomb, use Orange Guard, a natural pesticide derived from d-limonene (orange peel extract). Excellent against fleas, ants, and other small insects, Orange Guard ( is a human- and pet-friendly water-based product that may be used around food, both indoors and out.

Diatomaceous earth is another environmentally friendly alternative. It is a stainless, odorless powder that naturally dehydrates the insect instead of chemically poisoning it. From early times, humans used ashes, sand, or dust to keep insects off their crops. This product works similarly and can be used inside or outside. If you have carpet or rugs, sprinkle the powder on areas that harbor hard-to-reach fleas and watch them disappear.

Another valuable resource is the American Holistic Veterinarians Medical Association ( Many holistic veterinarians offer natural flea collars and sprays that do not use toxic pesticides. Natural products stores may also carry these items. Always check with your veterinarian and physician before using these products.

Also check the Pesticide Action Network of North America site (, which provides extensive information about pesticides and less toxic alternatives. The U.S. Department of Agriculture also offers a site, Integrated Pest Management ( that supplies tips about managing infestations.

Or, try this old-fashioned trick. My grandparents placed a baking sheet with some water covering the bottom near a small light on the floor overnight. The fleas were attracted to the light and jumped into the pan, becoming trapped in the water.

Caroline Blazovsky is a certified mold remediator, a member of the ACGIH and the IAQA, and the owner of My Healthy Home, a business that offers mold testing, indoor air testing, consultation, and home products.