Thanks for sticking with this while we worked out the best type of
global estimates to meet your needs.
I based the calculations below on statistics from the Census Bureau
for the category of "Plumbing and HVAC contractors" which, as I
mentioned earlier, includes drainage work as well:
2002 Economic Census
NAICS # estab- Total Total # emp-
code Activity lishments receipts payroll loyees
(000 $) (000 $)
23822 Plumbing/HVAC 87,501 118,740,885 35,942,262 974,368
The above numbers are for "payroll" companies...that is, companies
that have employees other than the owner him/herself.
Statistics for companies without employees -- that is, plumbers in
solo practice -- are listed separately:
2002 Economic Census
Plumbing, heating, and air-conditioning contractors
$5,920,986 total receipts (in thousands of dollars...in other words,
There are 87,501 payroll plumbing companies plus another 110,183
independent plumbers, for a total of 197,684 establishments of one or
This group earned a total of $118.74 billion (from the payroll
companies) and another $5.92 billion from the independent plumbers,
for total receipts of $124.66 billion.
To scale the US data up to the world as a whole, I did the following:
According to the World Bank:
Total GDP 2004
the total economic activity of the world as a whole (the gross
domestic product) was $40.887 trillion in 2004.
Of this amount, the US accounted for $11.667 trillion.
Put another way, the US accounts for 11.667 / 40.887 = 28.5% of the
world's total economic activity.
Assuming that proportion holds in the world of plumbing and drainage,
then 28.5% of the world's plumbers are at work in the United States,
while 71.5% of them work in other countries. Roughly speaking, for
every plumber at work in the US, there are almost three plumbers
working elswhere in the world.
Scaling up the numbers I gave you earlier leads to the following
Number of plumbing companies in the world: 197,684 / .285 = 693,628
Total plumbing receipts in the world: $124.66 billion / .285 =
$437.40 billion in plumbing receipts
As you mentioned in your earlier remarks, there are bound to be
differences between countries in terms of plumbers per capita,
contribution to GDP, and so on. But it's not unreasonable to suppose
that these differences might offset one another on a global scale. If
that's the case, then the estimates here can be taken as fairly
representative of the state of plumbing/drainage around the world.
I trust this information fully answers your question. However, please
don't rate this answer until you have everything you need. If you
would like any additional information, just post a Request for
Clarification to let me know how I can assist you further, and I'm at
All the best,
search strategy -- Used bookmark sites for census and GDP data