Post #G26: Back in the Town of Vienna, our water/sewer rate versus Fairfax County

This post only really matters if you use a lot of water outdoors during the summer.  Hence, it falls under gardening on this website.

People are often surprised to find out just how much water it takes to water a garden, or that running a lawn sprinkler for an hour typically consumes 1000 gallons.

And so, there’s sometimes some hubbub when the summer-quarter water bills come out, here in the Town of Vienna.  Particularly now, as Vienna is half-way through a planned five-year, 50% increase in the water/sewer rates.  People see an unusually high bill and attribute that to the rate increase.  When that may not be the whole story.

In 2018, when Vienna began to raise rates, it made the point that its rates were comparable to those of Fairfax County.  You can see that in Post #448, with citations of the Town of Vienna documents.

Oddly, I haven’t seen a mention of that recently, though I have hardly been keeping track of what’s going in town.  But after three years of rate increases here, and in Fairfax County, I thought it would be worthwhile to update that comparison of rates.  And to point out what I think is an issue for those who use a lot of water outdoors in the summer.

For the average user, the Town of Vienna combined water/sewer rate is now somewhat higher that Fairfax rate.  See table below.  But for anyone who uses a lot of waters outdoors in the summer, the Vienna rate is quite a bit higher.  The reason has to do with sewage charges for outdoor water use, versus “peak use charges” for high water use, in Fairfax versus Vienna.

That’s a bit of a snoozer for most people, so just cut down to the table at the bottom if you want to see the results.

Details follow.


Computation of water/sewer bills, Vienna versus Fairfax County

The Town of Vienna’s rate structure is fairly straightforward, for combined sewer-water customers in the Town of Vienna.  Quarterly meter readings are rounded to the nearest 1000 gallons.  There are three “tiers” of usage, and a different rate for each tier.  As you use more water during the quarter, you pay slightly higher rates per 1000 gallons for both water and sewer.  That’s as shown in the table at the end of this posting.  (Source:  Town of Vienna, current rates as published in InsideNova.)

The key fact for those who use a lot of water in summer is that you pay sewage charges for all the water that you use.  Even if you use that water outdoors, where it does not flow into the sanitary sewers (and so where, at least in theory, Vienna does not pay Fairfax (Edit:  WSSC?  I’m not sure which) for getting rid of it.)

Unless you are one of a few thousand Fairfax County residents who live outside the Town of Vienna, receive water from the Town of Vienna, but have Fairfax County sewer services.  For those individuals, Town of Vienna does the billing, but the sewer serves are provided under Fairfax County rules (below).  I’m going to ignore those “hybrid” customers for the rest of this discussion.

For Fairfax, it’s both simpler and more complicated.  There are no tiers.  There’s only one rate for water, and one rate for sewer. But.

But 1:  Peak water use charge.  If your (summer) water use exceeds your winter use by a lot (30% or 6000 gallons, whichever is larger), Fairfax adds on a peak use charge that more-than-doubles the cost of water use over that threshold.  That is supposed to cover the higher cost of supplying that peak summertime water.

But 2:  No additional sewage charge.  They only charge you for your typical wintertime sewer use.  That’s based on the theory that your excess summer use is used outdoors, and doesn’t enter the sanitary sewer system.

Despite those differences, it’s not hard to calculate the rates for a couple of use levels.

In the table below, I’ve used 15,000 gallons per quarter as my starting point.  That’s average quarterly use for a Town of Vienna residential customer (calculated from Page 12 of this Town of Vienna report (.pdf).

Then I’ve calculate the bills for 45,000 gallons of use in a quarter.  Assuming that 15,000 gallons is the “winter quarter” use that sets the Fairfax County thresholds for peak use charges and for sewage charges.  This is what a summer bill would look like if that same average Vienna residential customer used a standard lawn sprinkler for an hour a day, a little less than three times per week, for three months.

As you can see below, assuming I did the math right, Vienna is now slightly more expensive than Fairfax, for the average Vienna residential customer.  That’s to be expected, as we are in the middle of a five year plan to raise rates.  But if that customer has a large amount of outdoor summer use, Vienna is substantially more expensive.  This occurs because the net effect of the Fairfax rules is that you pay about $7 per 1000 gallons for that extra water ($3.20 base rate, $3.80 peak use charge, $0 sewage charge).  But in Vienna, you pay about $17 per 1000 gallons for that extra water ($7.05 water charge, $9.95 sewage charge).

Note that, coincidence or not, both Fairfax and Vienna are charging you about $7 per 1000 gallons for the additional summer water.  But Vienna adds another $10 for taking care of the (non-existent) sewage.  The net result is that at the higher rate, the Vienna bill approaches twice the Fairfax County bill.

At some level, it is what it is.  As long as Vienna’s rate do no more than cover costs, the money has to come from somewhere.  (Although, as costs include capital costs, some aspect of “cost” is discretionary.)

To me, purely subjectively, the Fairfax approach seems more like a square deal.  At each step, their goal seems to be to have you pay what it costs them.  The Vienna approach seems to have a little more social engineering embedded.  I got the impression that the consultant hired to set the rate plan was very much into water conservation.  And so, no slack on the rates charged for those with high summer use.

Whether or not my impression is true, Vienna and Fairfax County have very different approaches to high summer water use.  And I think that — and not the rate increase between last year and this year — probably explains the individuals who believe they’ve gotten an exceptionally high water bill for this past quarter.

Minor correction:  The Fairfax peak use charge is actually a nickel higher than what I showed above.  I’m not going back to re-create the table for that.