Tropical Gardening: Water Management in a Central Oahu yard

Last year I attended the City and County of Honolulu's 2019 Storm Water Quality BMPs Workshop.  The last day of the conference was my birthday and my treat to myself was to attend the sessions that most interested me, rather than the ones I knew the least about.  So I attended a panel discussion on rain barrels and a panel discussion on water reuse.

When we moved to our rental in Central Oahu, I read the CCH ordinances and State laws governing residential property and noted that washing machine water is considered a pollutant and illegal to discharge to the ground, as was any other domestic greywater.  I was not surprised the rules were the same in Maryland, had been adopted in most of Virginia.

But I grew up in southeastern Virginia, before the greywater rules were adopted and every summer Dad attached the sprinkler hose to the back of the washing machine, conveniently located in the furnace room on the back of the house and next to our vegetable garden.  The arm sprinkler would pulse around in its circle to the rhythm of the washer drum spin before springing back to its starting position.  We had droughts July through August and sometimes into September, but the roses, herb garden, and vegetables were always fine.  The vegetable garden was below the downstairs bathroom window, and every evening after my bath my mother would pass buckets of water out the window to my father in the garden (on the step ladder) and he would carefully pour the water along the trenches dug between the bean and tomato plants.  Occasionally a neighbor would report us to the City for obviously using water outside of the City's restrictions.  And the Water Utility inspector would sheepishly show up at the house, take my parents' statement, read the meter, observe the source of the water and apologize for the inconvenience.

The vegetable garden was important to us.  My mother planned the garden to provide enough canned vegetables to get us through the winter.  The walls of the old coal bin were lined with narrow closely spaced shelves and packed with mason jars of beans, tomatoes, cucumber pickles and corn every fall.

In my condo in Maryland I continued to water the balcony garden with bathtub water.

I was not careful about what I used in my bath and the plants received minimal rainwater due to the overhang of the balcony above.  I did dump the dirt from the annuals out into my rubbermaid storage bin compost pile every spring, stir the compost into the potting soil and refill the pots.  There was always more compost put back into the pots, and a decent amount of old potting soil left in the compost bin.  It absorbed the liquid from the compost, sped decomposition and reduced odors.  There was about one or two pots of material gained each year in this process, which I happily used up in new pots.  Either 6 years was not long enough for harmful salts from my bath products to accumulate or my spring remix reduced their effects.

The first garden in the house in Maryland was started for my balcony and started its outdoor life on the deck.

I continued watering them with bath tub water.  Eventually these went into the ground, and I continued hauling out the bathtub water and watering what I could.  We had that house for 6 years, and our water supply was a well and run through a water softener to reduce the naturally occurring radium.  I poured every shred of organic matter I could find into that garden, and that may have kept the softened well water from causing any problems.  I also had to get creative in moving plants around that yard after the first two years because every insect in the county discovered we did not spray and came to the free buffet.  By the time we moved to Hawaii, I had established mixed vegetable / flower / herb / perennial beds on every side of the house with a taxonomic family-based rotational plan.

Turns out my parent's and I were doing a lot of things wrong, at least according to Laura Allen's Greywater Green Landscape.  There are specific soaps and detergents to be used and most of my bath products to be avoided, and softened water never ever used, to avoid salt buildup in the soil and damage to plants.  You should also never spray greywater for human health reasons, and separate plumbing to code is required....

The house we are currently renting has an irrigation system which leaks like a sieve.  Whenever it is run water flows out the seam in the driveway apron and all of the front "weep holes" and our water bill doubles.  Due to COVID we put up a kiddie pool which periodically is drained and poured on the  yard.  And I still water the plants with bath tub water when everyone is healthy.  If this were my house the first thing I would do is install rain barrels at the four downspouts.  The downspouts are directly plumbed into the storm drain which is illegal in City and County of Honolulu.  The gutter in front of the house floods every time it rains heavily and the downspouts back up so we get waterfalls off the edge of the roof gutters.  The front and side yards are French-drained with the water shooting out the "weep holes" in the front wall and across the sidewalk into the gutter.  It is a ludicrous waste of water, particularly if the irrigation system is used because all that water goes straight out the French drains.

Update: Our first rental was sold out from under us. Amusingly the property manager made me pull out not only my garden but a significant portion of the herbaceous landscaping as well. So out new house, which had practically virgin beds all the way around the front and back yards, now has aloe, roses, amaryllis, ti, and 2 varieties of african irises ti all over. The new rental had 3 varieties of to and i added 3 more from the old rental. There is much more exposed dirt in the new yard which i am trying to cover with plants. Oh we also added 2 additional ferns to the mix. These downspouts are also plumbed into the storm drains illegally but the storm drains are plugged ao the water bubbles up through the grass in the front yard and overflows from the base of the downspout. Flooding the lanai alll the way around the house.  The water on the back lanai frequently comes up almost to the backdoor.