We can now view Census data from 2018 and earlier for Waikawa:
Find 2018 Census data about Waikawa (Horowhenua District) (find map boundary). Topics include population, ethnicity, religion, health, employment, income, education, and housing.
Source: Place Summaries | Waikawa (Horowhenua District) | Stats NZ.
Note: this isn’t just Waikawa Beach, but an area that encompasses from the southern boundary to roughly Hokio Beach Road and from around Takapu Road to the sea.
This area included 750 people and about half the houses were occupied private dwellings.
Number of people: 750
Median age: 51.7 years
Males: 378
Females: 369
Number of MΔori: 174
MΔori median age: 31.7 years
Occupied private dwellings: 333
Unoccupied private dwellings: 342
The rest of the data is very interesting too. I suggest you take a look for yourself.