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Grey Water Irrigation // Aguas Grises para Riego

Hello! What recommendations do you have for using grey water to irrigate garden crops? I just read this article from EDN#88, which was very helpful but I still have doubts. We would be using grey water to irrigate small home/kitchen gardens, relying on it primarily in the dry season when there is no other readily accessible source of water. According to the article, because the scale is so small there shouldn’t be too many problems with salt accumulation or pH change in the soil, which is good news, but then we arrive at the uncertainty of the safety of irrigating root crops and leafy vegetables. Considering that the purpose of these home gardens is to improve nutrition and child health, I want to be extra sure that our irrigation methods are not increasing the family’s exposure to pathogens. Furthermore, our roughly estimated irrigation needs will be a minimum of 5 gallons/day, and when the University of Massachusetts rule of thumb is extrapolated to our garden square footage (~32 sq ft) it gets us to about 2.3 gallons/day of grey water which the soil could handle, about half of what the garden needs.

Is this a viable option? Would you advise filtering the water before irrigating? Have you seen/implemented successful examples of household grey water filtration for irrigation? I am particularly interested in low input systems that would be simple to implement and care for. I liked the idea of passing the grey water through the compost pile/pit, but this seems to be an example of a safe way to discharge grey water rather than capturing it to water plants. Is there a low-tech way to pass grey water through compost and capture it on the other end after filtration?

Thanks for your help!


Hola! ¿Me pueden compartir sugerencias para el uso de las aguas grises para el riego de hortalizas? Acabo de leer este artículo que me ayudó mucho pero todavía me quedo con dudas. Usaríamos las aguas grises para regar huertos familiares pequeños, dependiendo de la cual durante la temporada seca cuando no dispone otra fuente buena de agua. Según el artículo, como es a escala pequeña, no esperamos encontrar muchos problemas con la acumulación de sal ni con cambios en el pH del suelo. Que bueno! Pero también hay que considerar la incertidumbre de la seguridad de regar tubérculos y verduras de hojas con aguas grises. Como el propósito de los huertos familiares es mejorar la nutrición y salud de los niños, quiero estar extra segura de que nuestros métodos de regar no aumentan su exposición a agentes patógenos. Además, estimamos que el huerto va a necesitar 5 galones/día, y cuando aplicamos la recomendación de la Universidad de Massachusetts a nuestro huerto (~32 pies cuadrados), nos da 2.3 galones/día de aguas grises que el suelo puede aguantar, solo la mitad de lo que requiere.

¿Es una opción factible? ¿Me aconsejan que filtre el agua antes de regar? ¿Han visto/implementado ejemplos exitosos de filtración de aguas grises para riego a nivel de la casa? Estoy interesada en sistemas de bajo insumo que serían sencillos para implementar y cuidar. Me gusta el idea de pasar el agua a través del compost, pero me parece que es un método seguro de verter el agua gris y no capturarla para regar. ¿Se puede pasar el agua a través del compost pero capturarla después de manera sencilla?

Gracias por su ayuda!

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@Brad_Ward do you have information?

I’ve added a few potentially helpful resources to a collection for graywater.
http://edn.link/pgx47x

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Hi Kelly! I"m also interested in this as we are planning to install a greywater drain/garden as part of the hand washing station in the Community Garden! I came across this today which you might find helpful. “WHO Guidelines for the Safe Use of Wastewater, Excreta and Greywater”.

Blessings!

Thanks so much, Steve!

Elliott! How exciting! What great news to hear that this is progressing. :slight_smile:
Thanks for the resource!

I grew up using grey water (bath or shower water only) for veggies. My grandmother said not to use dishwashing water.
However - ground up moringa seed will clean water to drinking level - so you could run it through that first. First you grow your moringa! And moringa is counter cyclical - so leaves are green during the drought cycle. Seriously in drought situations moringa can be a major help.
We always used chopped up material or plastic if available to prevent moisture loss. And water directly around the plant and lightly spray the leaves early in the morning. Moisture loss will defeat you if you water away from the plants and without cover.

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Thanks, Kate. I think your grandmother knew what she was doing. :smile: In reviewing the literature, the insoluble debris (which would mostly be found in used dish water) are usually the carrier for most pathogens in grey water. One study (Friedler, 2004) recommended excluding dish water because it only makes up 25-30% of total grey water volume, but contributes half of its COD content. And if the laundry water has been used to clean diapers or soiled bedclothes, it is likely to contain fecal matter. Bath/shower water seems to be the safest option, but hand washing after toilet use and showers can also contribute to the microbial contaminant load…and some studies have found that shower water can even carry the highest coliform count in comparison to other grey water sources (Rose et al. 1991).The high levels of contamination in grey water don’t necessarily correlate with edible crop contamination though as Finely (2008) investigates here and Jackson et al. (2006) investigates here. There are so many factors and so much that we don’t know! But it does seem that grey water can be used to irrigate food crops (even root crops!) when taking care to avoid direct water contact with plant surfaces and maintaining sanitary handling and cleaning post harvest.

Moringa would be great, but unfortunately it is too high and cold to grow here.

Absolutely, water conservation measures are key! Thanks for the advice!

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Hola Kelly,

Encontré varios vínculos de documentos en español que tal vez sean de ayuda:

Me cuentas si estos recursos de información te son de ayuda.
Bendiciones,

Cecilia

Gracias Cecilia!

El documento “Tecnologías para el uso sostenible del agua” me ayudó, en particular páginas 56-57 en la sección de reutilización del agua. Las referencias me dirigieron a dos documentos útiles: uno que se llama Experiencias en practicas de manejo de aguas servidas para la producción agrícola a pequeña escala y otro que se llama Filtro Artesanal de Aguas Grises para Riego por Goteo de la FAO. La segunda es un manual muy bueno de como construir un filtro de llantas con carbón, piedras, piedrín, y arena. @Elliott_Toevs, creo que algo así podría ser una buena opción para el Huerto Comunitario también!

Relacionada al filtro artesanal de llantas, encontré este documento: La Agricultura Urbana y su Contribución a la Seguridad Alimentaria: Sistematización del Proyecto Piloto AUP en Honduras, en que describe un proyecto que utilizó este tipo de filtro.

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¡Qué bien @Kelly_Wilson! Encontré otro documento muy bueno en la página de FAO-Guatemala, “Buenas Prácticas: Filtros Caseros de Aguas Grises”, y hasta unos videos: