Table 2.

Average turbidity level in rainwater before and after treatment.

City/regency area	Subdistrict/village	$\overline{X}$ before treatment (NTU)	$\overline{X}$ after treatment (NTU)	Drinking water requirement
Pontianak	Siantan Hulu	22.261	9.839	5 NTU
	Siantan Tengah	21.572	7.872
Kubu Raya	Limbung village	17.675	2.114
	Kuala Dua village	18.502	2.831
Mean		20.00	5.67
Median (min.-max.)		18.95 (15.06–26.81)	2.92 (0.14–14.96)
SD		3.33	5.15
P a	≤0.001 ∗

Source: primary data; ^aT-test (α = 5%); ^∗significant at p ≤ 0.05.