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Don't follow water polo except on the Cardboard.  Just curious, haven't checked (too lazy) to look up the national water polo landscape , er...waterscape.  My impression is that over the years, at the championship contention level,  this is a West Coast sport. Is the selection process a rigid regional structure or, does the playoff selection process even allow for an "unbalanced" representation to include the best-ranked teams?

"The 2018 National Collegiate Men’s Water Polo Championship is a four-team, single-elimination tournament. Six conferences
have been granted qualification into the bracket or opening-round structure and two teams will be selected at large. The top two
teams qualify directly into the national championship; the remaining six teams will compete for the last two championship berths
via four opening-round games, with the winners earning the remaining berths in the championship bracket."

There are 6 conferences with automatic qualifying: MPSF  (incl. the big 4 PAC-12 schools), Golden Coast Conf., Western Water Polo Association, Southern California Interscholastic Athletic Conference, College Water Polo Association (counts as  2 conferences in some way I don' know).

Water polo IN THE NCAA is primarily a West Coast sport, but it is very popular in some areas of the world.  It was included in the 1900 Olympics.
The non-West Coast schools in the current top 20 ranked teams are 10. Harvard, 13. Brown, 14.  Princeton, 17. Bucknell 19. George Washington, 20. Wagner.  I believe MIT may have been ranked in the past. Other teams in the top 20 include Pomona-Pitzer and California Baptist. 

While the sport of swimming is popular across much of the US, water polo seems to have a large youth contingent only in California, and then  primarily in SoCal.  It seems to be a relatively inexpensive sport for a school so smaller colleges can compete.   A few good players can bring success, but that draws upon the youths that have experience & skill  (ie, mostly S.Cal).  Schools can bring foreign athletes in to provide a strong base.

USC:  3xAustralia, 2xGreece, 2xCroatia,  1xHawaii, 18xS.Cal, 1xN.Cal
UCLA: 1xMontenegro, 1xHungary, 1xGeorgia(country), 1xFlorida,  1xOregon, 4xN. Cal, 22 S. Cal
Cal: 2xBrazil, 2xTurkey, 1xCroatia,  3xGreece,  1xAustralia,  1xTexas, 4xN.Cal, 10xS.Cal
Stanford: 1xHawaii, 1xWashington, 2xN.Cal, 16xS.Cal
Picking another ranked school  at  random:
Brown: 1xGreece, 2xConnecticut, 2xFlorida,  2xTexas, 1xMassachusetts, 7xS.Cal, 3xN.Cal (Menlo Park, Atherton, Los Altos)

(The multiples from one country were often for brothers.)

I hadn't thought about WP as a draw for schools to pull in WP players that weren't able to go to the top four schools but still wanted to compete.

I didn't realize the MPSF  has 39 schools involved, in 5 men's & 5 women's sports.  All men's NCAA  WP championships since 1992 have been from the MPSF.   In that time, the only non-Big Four to win was Pepperdine in 1997.  Before MPSF's  start in 1992, the previous non-Big Four winners were   1982 UC Irvine, 1979  UCSB, 1970  UC  Irvine.   (1969   is the earliest date at the NCAA site).  For women, it is since 2001 where all have been won by USC, UCLA, or Stanford.

While Stanford Men's WP has 10 NC titles, it has been a long drought.  The last win was 2002.

[M T]

Don't follow water polo except on the Cardboard.  Just curious, haven't checked (too lazy) to look up the national water polo landscape , er...waterscape.  My impression is that over the years, at the championship contention level,  this is a West Coast sport. Is the selection process a rigid regional structure or, does the playoff selection process even allow for an "unbalanced" representation to include the best-ranked teams?

"The 2018 National Collegiate Men’s Water Polo Championship is a four-team, single-elimination tournament. Six conferences
have been granted qualification into the bracket or opening-round structure and two teams will be selected at large. The top two
teams qualify directly into the national championship; the remaining six teams will compete for the last two championship berths
via four opening-round games, with the winners earning the remaining berths in the championship bracket."

There are 6 conferences with automatic qualifying: MPSF  (incl. the big 4 PAC-12 schools), Golden Coast Conf., Western Water Polo Association, Southern California Interscholastic Athletic Conference, College Water Polo Association (counts as  2 conferences in some way I don' know).

Water polo IN THE NCAA is primarily a West Coast sport, but it is very popular in some areas of the world.  It was included in the 1900 Olympics.
The non-West Coast schools in the current top 20 ranked teams are 10. Harvard, 13. Brown, 14.  Princeton, 17. Bucknell 19. George Washington, 20. Wagner.  I believe MIT may have been ranked in the past. Other teams in the top 20 include Pomona-Pitzer and California Baptist. 

While the sport of swimming is popular across much of the US, water polo seems to have a large youth contingent only in California, and then  primarily in SoCal.  It seems to be a relatively inexpensive sport for a school so smaller colleges can compete.   A few good players can bring success, but that draws upon the youths that have experience & skill  (ie, mostly S.Cal).  Schools can bring foreign athletes in to provide a strong base.

USC:  3xAustralia, 2xGreece, 2xCroatia,  1xHawaii, 18xS.Cal, 1xN.Cal
UCLA: 1xMontenegro, 1xHungary, 1xGeorgia(country), 1xFlorida,  1xOregon, 4xN. Cal, 22 S. Cal
Cal: 2xBrazil, 2xTurkey, 1xCroatia,  3xGreece,  1xAustralia,  1xTexas, 4xN.Cal, 10xS.Cal
Stanford: 1xHawaii, 1xWashington, 2xN.Cal, 16xS.Cal
Picking another ranked school  at  random:
Brown: 1xGreece, 2xConnecticut, 2xFlorida,  2xTexas, 1xMassachusetts, 7xS.Cal, 3xN.Cal (Menlo Park, Atherton, Los Altos)

(The multiples from one country were often for brothers.)

I hadn't thought about WP as a draw for schools to pull in WP players that weren't able to go to the top four schools but still wanted to compete.

I didn't realize the MPSF  has 39 schools involved, in 5 men's & 5 women's sports.  All men's NCAA  WP championships since 1992 have been from the MPSF.   In that time, the only non-Big Four to win was Pepperdine in 1997.  Before MPSF's  start in 1992, the previous non-Big Four winners were   1982 UC Irvine, 1979  UCSB, 1970  UC  Irvine.   (1969   is the earliest date at the NCAA site).  For women, it is since 2001 where all have been won by USC, UCLA, or Stanford.

While Stanford Men's WP has 10 NC titles, it has been a long drought.  The last win was 2002.