The effect of air flow through the second effect unit of upward-type, double-effect solar distillers on productivity has been investigated experimentally. Comparisons of productivities obtained from such open-type distillers with those from closed-type distillers (without air flowing through) have been made at various levels of insolation. It was found that considerable improvement in productivity was obtained for air flows at lower levels of insolation. It is believed that improvements in productivity may also be obtained if the air flow is limited to lower rates (i.e. less than 15 kg-m−1-h−1 in this study) when the levels of insolation are high (i.e. greater than 419kcal-m −2-h−1 in this study).