Available in laundry section of grocery store. Available in grocery stores and health food stores. Sold as liquid, flakes, powder or in bars. Bars can be grated to dissolve more easily in hot water. Insist on soap without synthetic scents, color or other additives.
Synthetic detergents cause more poisonings than any other household product.
Even phosphate-free, biodegradable laundry detergent contributes to water pollution. Disinfects, softens water. When using alternatives that have less hazardous ingredients, use and store with similar caution. Since these are strong chemicals, it's best to leave them alone. If you store a homemade mixture, make sure it is properly labeled.