Okay, so if we have an idea of what

is the average diameter of pipe that's in network.

Average being weighted by their individual lengths.

>> You mean for a whole city?

>> For a whole city, for a whole network and we

have a pretty good idea of what's the total length of pipe.

How do you get that?

Well, what's the length, length of streets?

If you're going to have house connections, you need a pipe in front of each of them.

In front, on, on each on each street.

So if we have an idea of what the total

length of the streets is, so that's the easy part.

What's the average diameter?

Depends on the size of the city.

In the United States, what drives the diameters of pipes is not so much

the hydraulic capacity, as much as the capacity that's needed for fighting fires.

That's not the case in developing countries.

In developing countries, even in pretty large cities,

the pipe network is designed to carry the flow.

That, that people are going to use

in their households and in their businesses, right?

So, and those pipes tend to be smaller than what we find in the industrialized.

>> So, we should be, should be cautious transferring it, cost estimates

from developing countries where fire's important

to, I mean, for industrialized countries.

>> [CROSSTALK] That would only apply to integrated systems.

If you think about these models we're developing.

We have a pipe cost function, cost per, per unit dip,

length is equal to alpha, the diameter of pipe raised to beta.

Okay.

The question I think you're raising is, let's be careful that we make sure that we

don't use average diameter pipe in industrialized countries

and assume that the average diameter of pipe.

>> Right.

>> In developing countries is going to be in the same ballpark.

It's not.

In developing countries there's going to be a predominance

of small diameter pipe, a lot of 2-inch diameter pipes.

In our town where you and I live,

the smallest diameter pipe is 6-inch diameter pipe.

In New York City, it used to be 8-inch diameter

pipe is the smallest diameter pipe, now it's about 10-inch.

So, on individual streets 10-inch pipe is the smallest diameter pipe.

In developing countries, even in large cities, in metro Manila, with millions and

millions of people, they've got tons of pipe that's two inches in diameter.

So if one were going to be replacing pipe in a, let's say, a neighborhood

of metro Manila, one would need to have an idea what's the smallest diameter pipe.

What's the largest diameter pipe?

So, and you get that from the engineers.

And then you make some guess, probably,

or an engineering preliminary design of the pipe

network to come away with some idea of what would be the average diameter pipe.

Then you go back to your individual cost function and use that to

predict what would be the cost of

the entire network in that particular neighborhood.

Given that you have an idea of what's the total length of streets and maybe

what the average diameter is depending on

where that net, where that neighborhood is located.

If it's located near the, the center of the city, you're going to have

large diameter pipe service way out in

the perforates, going to have small diameter pipes.

>> Can we, can we step back again and, and.

>> Sure.

>> And talk about the, this issue of economies of scale.

>> Yeah.

>> And your equation that means so, what can, can you tell us a little bit

more about and so, what you think of

as economies of scale and pipe water networks and.

>> Oh yeah.

Okay.

I've already alluded to this and maybe I'll try to sharpen it.