Water Usage and Conservation – Analysis

Water Usage and Conservation – Analysis

This fall, we plan to spend three nights boondocking at Franklin Mountains State Park outside El Paso, Texas. This park has no potable water, no dump station, no electricity. The park gates are only open 8:00 AM to 5:00 PM. No quick trips to get water and ice.

Before we go, we need to know what we need to be comfortable for 4 days and 3 nights in that park without having to leave the park to get water or visit a dump station.

Our slide-in truck camper tank capacities:

  • Fresh Water – 30 gallons
  • Grey Water – 20 gallons
  • Black Water – 18 gallons

We also have four 5 gallon potable water containers we can carry and use to fill our fresh water tank.

5 Gallon Potable Water Container with Spout
5 Gallon Potable Water Container with Spout

We are talking about bringing 2 gallons of bottled water per day as we don’t really trust our tanks for drinking water. Additionally, we plan to bring 20 pounds of ice in a Yeti Cooler to make our drinking water more refreshing.

Yeti Roadie 20 Cooler
Yeti Roadie 20 Cooler

Can we or how can we make it for 4 days and 3 nights with the tank capacities we have? 

Data Collection Recap

While we camped at Lake Brownwood State Park, Texas we collected water usage information to help us better understand our Water Usage and Conservation.

Standardized Activities

These are the standardized activities:

  • Overnight
    All activities that occur between the last reading before going to bed and the first reading after one is up in the morning.  This may include drinks of water, bathroom use and tooth brushing.
  • Navy Shower
    All activities associated with showering such as shaving, tooth brushing and navy showering.
  • Flush #1
    All activities associated with doing #1 in the bathroom including hand washing.
  • Flush #2
    All activities associated with doing #2 in the bathroom including hand washing.
  • Ready for bed
    All activities needed for getting ready for bed which can include tooth brushing, mouth wash, retainer rinsing, denture cleaning, etc.
  • Food Prep (not covered)
    All activities associated with food and drink.  Activities may include filling Brita Water Pitcher, filling coffee pot, rinsing dishes, washing dishes, filling dog water bowl, washing dishes, cleaning vegetables, etc.
  • Arrival (not covered)
    The starting point for a data set. Only useful for studies where the water meter isn’t starting out at zero.

When boondocking, we bring food along that doesn’t require water for cleanup.  We plan to have 2 gallons of water per day for drinking.  For this reason, Food Prep is not included or covered in the analysis.



Data was collected in a spreadsheet, transferred to a Microsoft Access Database and queried relentlessly.  The following table columns will be below the table.

Activity Days / Nights User Average Daily Activity Count Average Usage Average Daily Usage Total Stay Usage
Flush #1 4 LBP 5.5 0.1 0.6 2.4
Flush #2 4 LBP 1.2 0.8 1.0 4
Ready For Bed 3 LBP 1.0 0.8 0.9 2.7
Navy Shower 3 LBP 1.0 2.8 2.8 8.4
Flush #1 4 LMP 4.7 0.1 0.5 2
Flush #2 4 LMP 1.0 0.3 0.4 1.6
Ready For Bed 3 LMP 1.0 0.7 0.7 2.1
Navy Shower 3 LMP 1.0 4.0 4.0 12
Overnight 3 Both 1.0 0.5 0.6 1.8
Total Daily 11.5
4 Days and 3 Nights Stay Total 37

Table columns:

  • Activity
    One of the standard activities identified and defined under Standardized Activities above
  • Days/Nights
    The number of days or nights needed for the Total Stay Usage
  • User
    Which of us the activity applied to (Larry/LBP or Linda/LMP)
  • Average Daily Activity Count
    The average number of times during the day or night that the activity occurred
  • Average Usage
    The average amount of water in gallons used per activity occurance
  • Average Daily Usage
    The Average Daily Activity Count multiplied by the Average Usage
  • Total Stay Usage
    Computed from the product of Days/Night and Average Daily Usage, this column provides the expected usage for 4 days and 3 nights for the Activity and User

The data populating the table came from the Water Usage Spreadsheet.

Four Days and Three Nights

Can we actually make it for 4 days and 3 nights with the usage outlined above?

Fresh Water Tank

The 37 gallons of water used for the activities will come from the fresh water tank which holds 30 gallons.  We will need to bring at least 2 of our 5 gallon potable water tanks to extend our fresh water tank capacity to 40 gallons.

Black Water Tank

The black water tank is 18 gallons.  Flushes #1 and #2 are expected to generate 10 gallons for the black tank leaving 8 gallons of surplus capacity.  Surplus waste water tank capacity might come in handy later…

Grey Water Tank

The grey water tank is 20 gallons.   Ready For Bed, Navy Shower and Overnight activities are expected to generate 27 gallons of water for the grey tank.  Where does the extra 7 gallons of grey waste water go?

In our past boondocking adventures, we have used the dish pan to collect water from dish washing.  After the dishes were washed, we would dump the water into the toilet (black tank).  Using a similar approach, we could collect waste water used during Ready For Bed and Overnight to the dish pan and deposit in the toilet.  Unfortunately, at most, 4 gallons of water would be diverted.

Each of us could give up a shower or two.  When we both take Navy Showers, together on average we will use 6.8 gallons of water.  This is close enough to 7 gallons.  We could manage this.

Extending The Stay

In some Texas State Parks without sewer hookups, we have noticed people who attach regular hoses to their sewer outlet using an adapter similar to the one below.  Typically, the hoses go off into nearby bushes.

RV Waste Water Bayonet Fitting to Garden Hose Adapter
RV Waste Water Bayonet Fitting to Garden Hose Adapter

Dumping grey or black tanks on the ground in Texas State Parks is illegal and subject to fine.

We do have a portable waste water tank (see blog post Water and Electric Sites Don’t Have Sewer).  However, that solution won’t work at Franklin Mountains State Park because there is no dump station.  The nearest dump station could be 20 miles or more.  Much to far to drag the portable waste tank behind the Jeep.

For the two of us, the average daily total with navy showers is 11.5 gallons.  Not taking showers lowers the average daily total use to 4.7 gallons of which 2.5 gallons goes into the black tank and 2.2 goes into the grey tank.  At this rate, the black tank gets filled in 7 days.  The grey tank is filled in 9 days.  Assuming the black tank is the limiting factor here, the amount of fresh water used over 7 days would be 50.4 gallons.  This is 20 gallons over the fresh water tank capacity.  We can make up the 20 gallon short fall by bringing all four of our 5 gallon potable water containers.

Could we really go 7 days without bathing?  Not really.

Hope to see you on the road ahead!







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