A Review of On-Site Wastewater Treatment Systems in Western Australia from 1997 to 2011

Table 1

OWTS approved by LG (1997–2011).

System type	1997	1998	1999	2000	2001	2002	2003	2004	2005	2006	2007	2008	2009	2010	2011
Septic tank	322	546	782	795	618	630	655	687	556	616	693	753	615	688	626
ATU	49	61	73	50	36	44	63	125	189	149	177	197	155	241	214
Treatment plant	0	0	0	0	0	0	0	0	0	0	1	1	0	0	3
Composting toilet	2	0	0	2	3	2	2	0	1	3	3	1	1	1	2
Others	0	7	7	11	9	16	24	17	35	58	56	61	48	46	41
System not specified	130	90	3	14	60	49	41	54	43	72	18	20	13	11	39