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Table 2 Calculations for determining L. pneumophila distribution across various system compartments and effects of operating conditions

From: Water heater temperature set point and water use patterns influence Legionella pneumophila and associated microorganisms at the tap

Analysis Calculation Practical meaning/interpretation
Temperature effect on total planktonic loads (Table 3) \( \frac{{\left({\displaystyle \sum }{\left[\mathrm{L}\mathrm{p}\right]}_{\mathrm{Distal}}\times {\forall}_{\mathrm{Distal}}+{\left[\mathrm{L}\mathrm{p}\right]}_{\mathrm{Recirc}}\times {\forall}_{\mathrm{Recirc}}\right)}_{\mathrm{Control}}}{{\left({\displaystyle \sum }{\left[\mathrm{L}\mathrm{p}\right]}_{\mathrm{Distal}}\times {\forall}_{\mathrm{Distal}}+{\left[\mathrm{L}\mathrm{p}\right]}_{\mathrm{Recirc}}\times {\forall}_{\mathrm{Recirc}}\right)}_{\mathrm{Experimental}}} \) Factor by which planktonic L. pneumophila increase in the total system if the temperature is not elevated to the experimental setting
Temperature effect on the recirculating line and tank loads (Table 4) \( \frac{{\left({\displaystyle \sum }{\left[\mathrm{L}\mathrm{p}\right]}_{\mathrm{Recirc}}\times {\forall}_{\mathrm{Recirc}}\right)}_{\mathrm{Control}}}{{\left({\displaystyle \sum }{\left[\mathrm{L}\mathrm{p}\right]}_{\mathrm{Recirc}}\times {\forall}_{\mathrm{Recirc}}\right)}_{\mathrm{Experimental}}} \) Factor by which planktonic L. pneumophila increase in the recirculating portions of the system if the temperature is not elevated to the experimental setting
Temperature effect on distal tap loads (Table 3) \( \frac{{\left({\displaystyle \sum }{\left[\mathrm{L}\mathrm{p}\right]}_{\mathrm{Distal}}\times {\forall}_{\mathrm{Distal}}\right)}_{\mathrm{Control}}}{{\left({\displaystyle \sum }{\left[\mathrm{L}\mathrm{p}\right]}_{\mathrm{Distal}}\times {\forall}_{\mathrm{Distal}}\right)}_{\mathrm{Experimental}}} \) Factor by which planktonic L. pneumophila increase at the tap if the temperature is not elevated to the experimental setting
Re-growth in the recirculating lines (Fig. 3) [Lp]Recirc − [Lp]Inf Re-growth in the recirculating lines relative to the influent
Concentration (Fig. 4a) [Lp] L. pneumophila concentration
Factor increase (Fig. 4b) \( \frac{{\left[\mathrm{L}\mathrm{p}\right]}_{\mathrm{Distal}}}{{\left[\mathrm{L}\mathrm{p}\right]}_{\mathrm{Recirc}}} \) Re-growth in the distal taps relative to the recirculating line
Weekly yield (Fig. 4c) [Lp]Distal × Distal × Use Total amount of L. pneumophila delivered at the tap per week
Biofilm re-growth (Fig. 5) L. pneumophila in gene copies/cm2 Biofilm densities of L. pneumophila; because the same areas were re-swabbed, any L. pneumophila detected is assumed to have re-established during that experimental condition
  1. Lp: L. pneumophila concentration in gene copies/mL, Distal distal tap, Recirc recirculating line and tank, volume, Inf influent, Use use per week (21, 3, or 1)