Table 1 provides figures for the global production of desalinated water, by process and plant capacity. It shows that MSF plants have a higher total production capacity than any other process, despite the larger number of reverse osmosis plants. The growth and development of MSF plants owes a tremendous debt to the seminal contributions of the late Professor R. Silver of Glasgow University, who was the foremost pioneer of industrial scale distillation units. His first large-scale MSF units, in Kuwait and in Guernsey, were both commissioned in 1960. These plants had 19 and 40 stages respectively. Table 1 shows that, of the larger desalination plants (>4000 m³ d^-1), MSF plants amount to 64 per cent of the total capacity.

Table 1. Summary of worldwide desalination capacity to 1998, split by plant type and process capacity range.

Desalting process	Percentage	Capacity (×106 m3 d-1)	Capacity (106 gal d-1)	No. of plants
Unit capacity
100-60 000 m3 d-1
Multistage flash	44.4	10.02	2204	1244
Reverse osmosis	39.1	8.83	1943	7851
Multiple effect	4.1	0.92	202	682
Electrodialysis	5.6	1.27	279	1470
Vapor compression	4.3	0.97	213	903
Membrane softening	2.0	0.45	99	101
Hybrid	0.2	0.05	11	62
Others	0.3	0.06	13	120
	100.0	22.57	4965	12 433
Unit capacity
500-60 000 m3 d-1
Multistage flash	46.8	10.00	2200	1033
Reverse osmosis	37.9	8.10	1782	3835
Multiple effect	3.8	0.81	178	653
Electrodialysis	4.7	1.00	220	230
Vapor compression	4.2	0.90	198	486
Membrane softening	2.1	0.45	99	64
Hybrid	0.2	0.04	9	27
Others	0.23	0.05	11	11
EDI	0.05	0.01	2	97
	100.0	21.36	4699	6436
Unit capacity
4000-60 000 m3 d-1
Multistage flash	64.0	9.27	2039	496
Reverse osmosis	25.7	3.72	818	613
Multiple effect	3.6	0.52	114	48
Electrodialysis	2.1	0.31	68	60
Vapor compression	1.9	0.28	62	42
Membrane softening	2	0.36	79	50
Hybrid	0	0.02	4	2
Others	0	0.00	0	0
	100.0	14.48	3186	1311

Source: 1998 IDA Wordwide Desalting Plants. Inventory Report No. 15. Wangnick Consulting GmbH.

Table 2 splits the data in a different way to indicate the disproportionately large share of the world's desalination capacity which is in the Arab states, and particularly in the Arabian Gulf.

Table 2. Summary of worldwide desalination capacity, to 1998 showing contribution made by Arab nations.

AGCC = Arabian Gulf Co-operation Council.
Source: 1998 IDA Wordwide Desalting Plants. Inventory Report No. 15. Wangnick Consulting GmbH.

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