Sunday, July 25, 2010

Water Harvesting Update

We've had 2.07" of rain so far this summer -- .67" at the end of June, and 1.40" so far this month.  It's been a dry monsoon so far.  Fortunately, I've managed to get all my water tanks optimized for maximum water collection.  This picture shows my original 1000-gallon tank, and how water from two separate roofs feeds into it.  I just added the right-hand gutter a couple of weeks ago.  On the left gutter, you can see that I'm starting to add gutter guards to keep leaves out of the gutter.  Eventually I'll have all my gutters guarded.  The pipe on the right handles any overflow.  In an earlier post I showed how it's possible to use grade-school math to figure out how much water each tank collects for every inch of rain.  This is a great way to keep tabs on the water tank situation as the monsoon goes along.  This particular tank collects 158 gallons of water for every inch of rain. 

This is the 1000-gallon tank I installed last winter behind the tool shed.  Two separate roofs, at two levels, means I have two gutters feeding into the tank.  This one collects 186 gallons per inch of rain.

This is the 1100-gallon tank that collects water from the ark roof.  I installed it last winter.  It stores 239 gallons per inch of rain.  The downspout looks flimsy, but the ends are screwed into place which makes it surprisingly strong.

At the present time I have four tanks totalling 3300 gallons.  These four tanks collect a total of 706 gallons for every inch of rain, which means that so far this monsoon I've collected over 1460 gallons of rainwater.  This sounds like a lot, but is actually minimal for irrigation purposes.  Next winter I plan to install another 1000-gallon tank that will store the water from four roofs.  This will add considerably to my water-storing capability.  In fact this will be my "go-to" tank during the summer, since it should fill up after any decent rain.

I live right on the Rio Grande, so I have access to unlimited water as long as the river flows.  Unfortunately the groundwater is salty and alkaline, and not suitable for anything other than emergency irrigation, so I'm more dependent on the river than I'd like to be.  I fully expect that eventually (maybe even next winter, which is predicted to be dry) the snowpack will fail and the river won't flow for the entire summer.  The fact that this hasn't happened in the 37 years I've lived here doesn't mean it won't happen in the future.  So I'm motivated to harvest as much rainwater as I possibly can.

Heavy rain last night:  the first region-wide rain of the summer so far -- from Las Cruces north to the Sierra County line.  We had 1.61", which added over 1130 gallons to my water collection.  Both of our arroyos ran, and the river ran bank-full but didn't quite flood.  I would call this one a heavy rain, but nothing unusual.

According to the Las Cruces Sun-News, this was a record-breaking 2-day rain -- 3.34 inches at NMSU.  What's exciting for me is the rainfall total at Rasaaf Hills west of Mesilla, where I have 8 beehives -- 3.59 inches.  The sandy soil in this area becomes covered with yellow carpets of Limoncillo (an excellent honey plant) after heavy rains.  Now, for maybe an inch of rain a week to help develop the crop...